Principles and Recommendations for Population and Housing

Principles and

Recommendations for

Population and Housing

Censuses

Revision 3

United Nations

New York, 2017

Department of Economic and Social Aﬀairs

Statistics Division

ST/ESA/STAT/SER.M/67/Rev.3

Department of Economic and Social Aﬀairs

e Department of Economic and Social Aﬀairs of the United Nations Secretariat is a vital

interface between global policies in the economic, social and environmental spheres and

national action. e Department works in three main interlinked areas: (a) it compiles,

generates and analyses a wide range of economic, social and environmental data and

information on which States Members of the United Nations draw to review common

problems and to take stock of policy options; (b) it facilitates the negotiations of Member

States in many intergovernmental bodies on joint courses of action to address continuing or

emerging global challenges; and (c) it advises interested Governments on the ways and means

of translating policy frameworks developed in United Nations conferences and summits

into programmes at the country level and, through technical assistance, helps build national

capacities.

Notes

e designations used and the presentation of material in this publication do not imply the

expression of any opinion whatsoever on the part of the Secretariat of the United Nations

concerning the legal status of any country, territory, city or area, or of its authorities, or

concerning the delimitation of its frontiers or boundaries.

e term “country” as used in this publication also refers, as appropriate, to territories or

areas.

e designations “developed regions” and “developing regions” are intended for statistical

convenience and do not necessarily express a judgement about the stage reached by a

particular country or area in the development process.

Symbols of United Nations documents are composed of capital letters combined with ﬁgures.

Mention of such a symbol indicates a reference to a United Nations document.

United Nations Publication

ST/ESA/STAT/SER.M/67/Rev.3

Sales No. E.15.XVII.10

ISBN 978-92-1-161597-5

eISBN 978-92-1-057394-8

Printed by the United Nations, New York

iii

Preface

Since its earliest years, the United Nations has issued a series of international principles and

recommendations on population and housing censuses to assist national statistical oﬃces

and census oﬃcials, throughout the world, in planning and carrying out improved and

cost-eﬀective censuses. e ﬁrst set of principles and recommendations for population and

housing censuses was issued in 1958 at the request of the Statistical Commission of the

United Nations in response to a need for developing international standards and as a corner

stone of the ﬁrst World Population and Housing Census Programme. Although the scope of

these recommendations has evolved over time in response to current practices and national

needs, they usually provide guidance on the main characteristics of population and housing

censuses, general material on census operations and methods and more detailed guidance on

the content of censuses.

Over the years, the United Nations Statistics Division has played a pivotal role in

the coordination of the World Population and Housing Census Programme by issuing and

revising international recommendations, providing technical assistance to countries in census

operations, and compiling and disseminating census results from countries or areas. e last

global census recommendations were published in 2008 under the title Principles and Recom

mendations for Population and Housing Censuses, Revision 2.

Noting that this publication is a vital resource for countries in planning and con-

ducting their population and housing censuses, the Statistical Commission, at its forty-third

session,

welcomed the suggestion to initiate early enough a programme of work for the third

revision of the Principles and Recommendations for Population and Housing Censuses, in prepa

ration for the 2020 World Population and Housing Census Programme.

e current revision of the principles and recommendations was carried out by an

expert group comprising census experts representing all regions of the world, whose contribu

tions were organized around the following working groups and subgroups:

1) Working Group on Population and Housing Topics: (i) Subgroup on Population

Topics, (ii) Subgroup on Housing Topics;

2) Working Group on Census Planning and Methodology: (i) Subgroup on Census

Operations, (ii) Subgroup on Use of Technology in the Census, (iii) Subgroup on

Alternative Censuses; and

3) Working Group on Census Products and Data Utilization.

As Secretariat of the World Population and Housing Census Programme, the

United Nations Statistics Division coordinated the revision process for the current revision.

is was done mainly through convening two meetings of the expert group

to review the

text of the Principles and Recommendations for Population and Housing Censuses, Revision 2

and prepare the third revision of the Principles and Recommendations for Population and Hous

ing Censuses taking into account contemporary practices in census taking. At its forty-sixth

session in 2015, the United Nations Statistical Commission adopted the draft Principles and

Recommendations for Population and Housing Censuses, Revision 3 and encouraged countries

United Nations publication,

Sales No. E.07.XVII.8.

Oﬃcial Records of the Economic

and Social Council, Supplement

No. 4, E/2012/24-E/CN.3/2012/34

(2012), chapterI, paragraph 2.

Reports of expert group

meetings, available from

http://unstats.un.org/unsd

/demographic/meetings/egm

/default.htm.

Principles and Recommendations for Population and Housing Censuses, Revision 3iv

to begin its implementation keeping in mind the importance of setting quality standards for

the conduct of the census.

e salient features of the draft Principles and Recommendations for Population and

Housing Censuses, Revision 3 compared to Revision 2 include a restructuring of the guidelines

to make them more intuitive and user-friendly by following as closely as possible the Generic

Statistical Business Process Model.

Consequently, the revised draft is divided into four parts:

Part one: Essential features and census methodology; Part two: Planning, organization and

management; Part three: Census operation activities; and Part four: Population and housing

census topics.

e revised census recommendations also provide more elaboration on alternative

methodologies to the traditional census for producing census statistics based on national

experiences of the 2010 census round and also introduce major changes to concepts and

terminology related to economic characteristics in accordance with the new International

Labour Organization conceptual framework for work statistics.

In addition, the current

revision includes an entirely new chapter on the use of technology in census operations,

owing mainly to the increasing and signiﬁcant use of advanced technologies, in all phases of

the census, as countries aspire to increase overall response, quality and timeliness of census

data. Other notable changes include sections on archiving of individual records, and on the

overall evaluation of the census.

Unlike its predecessor, the Principles and Recommendations for Population and Hous

ing Censuses, Revision 3 does not contain tabulation shells. Instead, the accompanying set of

tabulations is posted on the United Nations website.

In the context of the importance of statistical information for development policy

formulation and monitoring, the Principles and Recommendations for Population and Hous

ing Censuses, Revision 2 contained a section on development indicators, which referred to

the use of census data for monitoring of the Millennium Development Goal indicators. At

the ﬁnalization of the Principles and Recommendations for Population and Housing Censuses,

Revision 3, the international community was actively engaged in discussions on the post-2015

development agenda and a new set of global development goals that would succeed the Mil

lennium Development Goals after 2015. While a set of proposed sustainable development

goals and their targets was submitted to the General Assembly in September 2014,

the exact

scope and content of the new development agenda is yet to be agreed upon among Member

States, pending the United Nations Sustainable Development Summit, 25-27 September

2015, New York, United States of America. Consequently, the expert group recommended

that the section on development indicators be appropriately modiﬁed once complete informa

tion on sustainable development goals, targets and indicators becomes available, to be issued

as an addendum to the print publication.

Oﬃcial Records of the Economic

and Social Council, Supplement

No. 4, E/2015/24-E/CN.3/2015/40

(2015), chapter I, section C,

decision 46/102, available from

http://unstats.un.org/unsd

/statcom/doc15/Report-E.pdf.

See www1.unece.org/stat

/platform/display/GSBPM

/GSBPM+v5.0.

Nineteenth International Confer-

ence of Labour Statisticians,

Resolution Concerning Statistics

of Work, Employment and Labour

Underutilization (Geneva, 2013).

The Road to Dignity by 2030: End-

ing Poverty, Transforming All Lives

and Protecting the Planet. Synthe-

sis report of the Secretary-Gen-

eral on the post-2015 sustainable

development agenda, paragraph

51 (A/69/700, presented at the

General Assembly, Sixty-ninth

Session).

United Nations Expert Group

Meeting on Revising the Principles

and Recommendations for

Population and Housing Cen-

suses Meeting Report, New York,

29April-2 May 2014, available

from http://unstats.un.org/unsd

/demographic/meetings/egm

/NewYork/2014/report.pdf.

Acknowledgements

e United Nations Statistics Division expresses its appreciation to the members of the expert

group on the 2020 World Population and Housing Census Programme for their contribution

to the revision of these recommendations. e expert group was chaired by Marc Hamel

(Canada) and comprised of three working groups and ﬁve sub-groups with the following

lead experts:

• Ian White (United Kingdom), Working Group on Population and Housing

Topics

— Andrew Mukulu (Uganda), Subgroup on Population Topics

— Arona Pistiner (United States), Subgroup on Housing Topics

• C. Chandramouli (India), Working Group on Census Planning and Methodology

— Feng Nailin (China), Subgroup on Census Operations

— Andrea Diniz da Silva (Brazil), Subgroup on Use of Technology in the Census

— Sven Ake Gunnar (Sweden), Subgroup on Alternative Censuses

• Pali Lehohla (South Africa), Working Group on Census Products and Data Uti

lization

e revision beneﬁted from the vital contribution of numerous census experts from

national statistical oﬃces and from subregional, regional and international organizations:

Duncan Young (Australia), Jane Badets (Canada), Soﬁa Mora Steiner (Costa Rica), Emad

Nassif Mahrous (Egypt), Stefan Schweinert-Albinus (Germany), David Yenukwa Kombat

(Ghana), Sairi Hasbullah (Indonesia), Fabio Crescenzi (Italy), Valerie Nam (Jamaica), Rozita

Talha (Malaysia), Argisoﬁa Perez Moreno and Elsa Resano Pérez (Mexico), Amarbal Avirmed

(Mongolia), Liina Ndafewayo Kaﬁdi (Namibia), Yaqoob Al Zadjali (Oman), Moran Flores

Gaspar Humberto and Juan Valverde Quezada (Peru), Minerva Eloisa Esquivias (Philip

pines), Hyungseog Kim (Republic of Korea), Svetlana Nikitina (Russian Federation), Celia de

Klerk (South Africa), Jorge Luis Vega Valle (Spain), Abdallah Najjar (State of Palestine), Ear

tha Groenfelt (Suriname), Furkat Mirpochchoev (Tajikistan), Sebnem Canpolat and Dilek

Guder (Turkey), Aisha Al Ali and Abdulla Hassan Abdulla Al Shaer (United Arab Emir

ates), Garnett Compton (United Kingdom), Maurice Mubila (African Development Bank),

Giampaolo Lanzieri and David orogood (Eurostat), Jairo Castano and Pietro Gennari

(FAO), Elisa Benes (ILO), Arthur Jorari (Secretariat of the Paciﬁc Community), Arman Bidar

Bakhtnia (SIAP), Patrick Gerland and Clare Menozzi (United Nations Population Division),

Raj Gautam Mitra (UNECA), Paolo Valente (UNECE), María-Isabel Cobos and Magda

Ruiz (UNECLAC), Friedrich Huebler (UNESCO Institute for Statistics), Ralph Hakkert,

Samson Lamlenn and Sabrina Juran (UNFPA), Gora Mboup (UN-HABITAT), Tarek Abou

Chabaké (UNHCR), Julie Weeks and Mitch Loeb (Washington Group).

e United Nations Statistics Division, as Secretariat of the World Population and

Housing Census Programme, coordinated the revision process, including organization of

expert group meetings, review of text and preparation of the publication. e following staﬀ

Principles and Recommendations for Population and Housing Censuses, Revision 3vi

contributed to the revision process: Keiko Osaki-Tomita, Srdjan Mrkic, Margaret Mbogoni,

Seiﬀe Tadesse and Meryem Demirci.

e United Nations Statistics Division appreciates the close collaboration and con

tribution of the UNECE to the revision of the principles and recommendations, particularly

with regard to eﬀorts taken to ensure harmonization, to the extent possible, between the

European and the global census recommendations for the 2020 round of population and

housing censuses.

vii

Contents

Page

Preface .................................................................. iii

Acknowledgements ........................................................ v

Introduction .............................................................. xv

Part one. Essential features and census methodology

Chapter

I. Essential roles of the census............................................. 1

II. Deﬁnitions and essential features ........................................ 2

A. Deﬁnitions ...................................................... 2

1. Population census ............................................. 2

2. Housing census ............................................... 3

B. Essential features.................................................. 3

1. Individual enumeration......................................... 3

2. Universality within a deﬁned territory.............................. 3

3. Simultaneity ................................................. 3

4. Deﬁned periodicity ............................................ 3

5. Capacity to produce small-area statistics ............................ 4

III. Uses of population and housing censuses .................................. 4

A. Uses of population censuses ......................................... 5

1. Uses for policymaking, planning and administrative purposes ........... 5

2. Uses for research purposes ...................................... 6

3. Uses for business, industry and labour ............................. 6

4. Uses for boundary delimitation................................... 6

5. Use as a sampling frame for surveys ............................... 6

B. Uses of housing censuses ............................................ 7

1. Uses for development of benchmark housing statistics ................. 7

2. Uses for the formulation of housing policy and programmes ............ 8

3. Assessment of the quality of housing............................... 8

C. Relationship between the population census

and the housing census ............................................. 8

D. Relationship of population and housing censuses to intercensal sample surveys .. 9

E. Relationship of population and/or housing censuses to other types of censuses

and other statistical investigations..................................... 10

1. Census of agriculture........................................... 10

2. Census of establishments........................................ 11

3. Census of buildings ............................................ 12

Principles and Recommendations for Population and Housing Censuses, Revision 3viii

4. System of current housing statistics................................ 12

5. Civil registration and vital statistics................................ 12

6. Administrative data sets ........................................ 13

IV. Census methodology .................................................. 13

A. Full ﬁeld enumeration (traditional census) .............................. 15

B. Register-based census .............................................. 17

1. Register source with existing sample survey ......................... 18

2. Necessary conditions ........................................... 19

3. Advantages and disadvantages.................................... 19

4. Some considerations for census taking and content.................... 20

C. Combined methodologies ........................................... 21

1. Necessary conditions........................................... 21

2. Advantages and disadvantages.................................... 22

3. Some considerations for census taking and content.................... 22

4. Examples of combined methodologies.............................. 23

5. Some considerations for census taking and content.................... 25

V. Operational aspects for register-based census or combined methodology ........ 25

A. General aspects and preconditions .................................... 25

B. Collection and processing ........................................... 27

VI. Use of sampling in population and housing censuses ......................... 28

A. Features of acceptable sampling operations .............................. 28

B. Census resources .................................................. 29

Part two. Planning, organizing and management

I. Introduction ......................................................... 31

II. Overall census planning................................................ 31

III. Strategic objectives and management .................................... 32

A. Strategic objectives ................................................ 32

B. Strategic management .............................................. 34

C. Avoiding gender biases and biases aﬀecting indigenous peoples and minorities .. 36

IV. Units, place and time of enumeration ..................................... 36

A. Units of enumeration .............................................. 36

1. Person ...................................................... 37

2. Household................................................... 38

3. Population in collective living quarters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4. Building .................................................... 39

5. Living quarters ............................................... 39

B. Place of enumeration ............................................... 40

1. Concepts relating to the place of enumeration ....................... 40

2. Operational issues relating to the place of residence and the place

of enumeration ............................................... 41

C. Enumeration point of time .......................................... 43

D. Time reference period for data on the characteristics of the population

and of living quarters .............................................. 44

PageChapter

ixContents ix

V. Legal basis .......................................................... 44

VI. Financial management ................................................ 45

A. Financial basis for censuses .......................................... 45

B. Budget and cost control............................................. 46

VII. Administrative organization ............................................ 48

A. Overall overview .................................................. 48

B. Statistical leadership ............................................... 49

VIII. User consultation, communication and publicity ............................ 50

IX. Census calendar ...................................................... 53

X. Human resources management.......................................... 54

XI. Logistics management................................................. 56

A. Procurement management........................................... 56

B. Forward and reverse logistics......................................... 58

XII. Contracting out ................................................................... 59

XIII. Use of technology ................................................................ 62

XIV. Quality assurance ................................................................ 66

A. Plans for quality assurance .......................................... 66

B. Quality assurance components ....................................... 67

C. Need for a quality management system for the census process ............... 69

D. e role of managers ............................................... 70

E. Quality improvement and the census .................................. 72

1. Topic selection................................................ 73

2. Form design and testing ........................................ 73

3. Field operations ............................................... 74

4. Processing ................................................... 75

5. Dissemination ................................................ 75

6. Evaluation ................................................... 76

Part three. Census operation activities

I. Introduction ......................................................... 79

II. Census questionnaires: content and design ................................ 79

III. Building census infrastructure........................................... 84

IV. Mapping and geospatial data ........................................... 85

A. Strategic planning ................................................. 85

B. e role of maps in the census........................................ 86

C. Census geography ................................................. 87

D. Technology for census mapping ...................................... 90

E. Geographic information systems...................................... 93

F. Contracting out for census mapping ................................... 94

G. Implementation of census-mapping programme .......................... 95

H. Maps for dissemination purposes ..................................... 97

PageChapter

Principles and Recommendations for Population and Housing Censuses, Revision 3x

V. Census tests ......................................................... 98

VI. Living quarters and household listing ..................................... 99

VII. Field enumeration .................................................... 100

A. Method of enumeration ............................................ 100

B. Timing and length of the enumeration period ........................... 103

C. Management and supervision ........................................ 104

D. Use of technology ................................................. 106

VIII. Data processing................................................................ 108

A. Method of processing .............................................. 109

B. Preparation for data capture ......................................... 110

C. Data capture ..................................................... 111

D. Coding ......................................................... 112

E. Data editing ..................................................... 114

F. Validation ....................................................... 115

G. Processing control ................................................. 116

H. Master ﬁle ....................................................... 116

I. Methods of tabulation.............................................. 117

IX. Evaluation of the results................................................ 118

A. Purpose of census evaluation......................................... 118

B. Methods of census evaluation ........................................ 119

C. Post-enumeration survey ............................................ 120

D. Demographic analysis for census evaluation ............................. 122

E. Acceptance of results ............................................... 123

X. Census products, data dissemination and utilization ......................... 123

A. Introduction ..................................................... 123

B. Plans for census products and data dissemination......................... 124

1. Developing a dissemination strategy ............................... 124

2. Tabulation programme ......................................... 127

3. Dissemination geography ....................................... 128

4. Mode of dissemination of outputs................................. 130

5. Conﬁdentiality and privacy...................................... 133

6. Metadata .................................................... 134

7. Promotion of, and training on, uses of census data .................... 135

C. Census data dissemination: products and services......................... 136

1. Provisional and ﬁnal results...................................... 136

2. Census reports................................................ 137

3. Databases ................................................... 140

4. Geographic products ........................................... 144

5. Interactive electronic outputs .................................... 148

6. Microdata dissemination........................................ 149

7. Customized products .......................................... 153

8. General interest and special audience products ....................... 154

D. Census data utilization ............................................. 156

1. General uses of population and housing censuses ..................... 156

2. Analysis of the results .......................................... 158

3. Cross-cutting and emerging social issues............................ 159

4. Development indicators......................................... 164

PageChapter

xiContents xi

Page

XI. Documentation of census experience ..................................... 165

XII. Archiving individual records ............................................ 166

A. Purpose of archiving individuals records................................ 166

B. Procedures for archiving ............................................ 166

C. Archiving individual records and microdata ............................. 167

XIII. Overall evaluation of the census ......................................... 168

A. Importance of evaluations ........................................... 168

B. Planning for the evaluation .......................................... 168

Part four. Population and housing census topics

I. Population census topics ............................................... 171

A. Factors determining the selection of topics .............................. 171

1. National priority .............................................. 172

2. International comparability...................................... 172

3. Suitability ................................................... 173

4. Resources ................................................... 173

5. Alternative sources............................................. 173

B. List of topics ..................................................... 173

C. Population count.................................................. 176

1. Population present count........................................ 177

2. Usual resident population count .................................. 178

3. Other population counts ........................................ 180

4. Diﬃcult-to-enumerate groups .................................... 180

D. Deﬁnitions and speciﬁcations of topics ................................. 182

1. Geographic and internal migration characteristics .................... 182

1.1. Place of usual residence (core topic) ............................ 183

1.2. Place where present at time of census (core topic) ................. 183

1.3. Place of birth (core topic) .................................... 184

1.4. Duration of residence (core topic) ............................. 185

1.5. Place of previous residence (core topic) ......................... 185

1.6. Place of residence at a speciﬁed date in the past (core topic).......... 186

1.7. Total population (core topic) ................................. 186

1.8. Locality (core topic) ........................................ 187

1.9. Urban and rural (core topic) ................................. 188

2. International migration characteristics ............................. 189

2.1. Country of birth (core topic) ................................. 190

2.2. Country of citizenship (core topic)............................. 191

2.3. Acquisition of citizenship.................................... 191

2.4. Year or period of arrival in the country (core topic) ................ 192

3. Household and family characteristics .............................. 192

3.1. Relationship to the reference person of household (core topic)........ 193

3.2. Household and family composition (core topic)................... 196

3.3. Household and family status ................................. 198

4. Demographic and social characteristics............................. 199

4.1. Sex (core topic)............................................ 199

4.2. Age (core topic) ........................................... 200

Chapter

Principles and Recommendations for Population and Housing Censuses, Revision 3xii

Page

4.3. Marital status (core topic) ................................... 201

4.4. Ethnocultural characteristics ................................. 203

4.5. Religion ................................................. 203

4.6. Language ................................................ 204

4.7. Ethnicity ................................................ 204

4.8. Indigenous peoples......................................... 205

4.9. Disability characteristics .................................... 206

5. Fertility and mortality.......................................... 210

5.1. Children ever born alive (core topic) ........................... 212

5.2. Children living (core topic) .................................. 213

5.3. Date of birth of last child born alive (core topic) .................. 214

5.4. Births in the past 12 months ................................. 214

5.5. Deaths among children born in the past 12 months ............... 215

5.6. Age, date or duration of ﬁrst marriage .......................... 215

5.7. Age of mother at birth of (date or time since) ﬁrst child born alive .... 215

5.8. Household deaths in the past 12 months (core topic)............... 216

5.9. Maternal or paternal orphanhood ............................. 216

6. Educational characteristics ...................................... 217

6.1. Literacy (core topic) ........................................ 217

6.2. School attendance (core topic) ................................ 218

6.3. Educational attainment (core topic)............................ 219

6.4. Field of education and educational qualiﬁcations ................. 221

7. Economic characteristics ........................................ 222

7.1. Introduction ............................................. 222

7.2. Conceptual framework for work statistics ....................... 223

7.3. Labour force status (core topic) ............................... 226

7.4. Characteristics of jobs and establishments ....................... 232

7.5. Status in employment (core topic) ............................. 233

7.6. Occupation (core topic) ..................................... 235

7.7. Industry (core topic)........................................ 235

7.8. Place of work ............................................. 236

7.9. Institutional sector of employment ............................ 237

7.10. Work ing t ime............................................. 238

7.11. Participation in own use production of goods (core topic) ........... 239

7.12 . I ncome .................................................. 240

8. Agriculture .................................................. 240

8.1. Introduction ............................................. 240

8.2. Own-account agriculture production .......................... 241

8.3. Characteristics of all agricultural activities during the last year....... 241

II. Housing census topics ................................................. 242

A. Factors determining the selection of topics .............................. 242

1. National priority .............................................. 244

2. International comparability...................................... 244

3. Suitability ................................................... 244

4. Resources ................................................... 245

5. Alternative sources............................................. 245

B. List of topics ..................................................... 245

xiiiContents xiii

Page

C. Deﬁnitions and speciﬁcations of topics ................................. 247

1. Living quarters—type of (core topic) .............................. 247

1.1. Deﬁnition of living quarters ................................. 247

1.2. Classiﬁcation of living quarters ............................... 247

1.3. Deﬁnitions of each type of living quarters ....................... 249

1.4. Housing units ............................................ 249

1.5. Collective living quarters .................................... 254

2. Location of living quarters (core topic) ............................. 255

2.1. Address ................................................. 256

2.2. Locality ................................................. 256

2.3. Urban and rural........................................... 256

3. Occupancy status (core topic) .................................... 256

4. Ownership—type of (core topic).................................. 257

5. Rooms—number of (core topic) .................................. 258

6. Bedrooms—number of ......................................... 258

7. Useful ﬂoor space ............................................. 258

8. Water supply system (core topic) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259

9. Drinking water—main source of (core topic) ........................ 260

10. Toilet—type of (core topic) ...................................... 261

11. Sewage disposal (core topic) ..................................... 261

12. Solid waste disposal—main type of (core topic) ...................... 262

13. Bathing facilities (core topic) ..................................... 262

14. Kitchen—availability of (core topic) ............................... 263

15. Fuel used for cooking (core topic) ................................. 264

16. Lighting and/or electricity—type of (core topic) ...................... 264

17. Heating—type and energy used .................................. 264

18. Hot water—availability of....................................... 265

19. Piped gas—availability of ....................................... 265

20. Use of housing unit ............................................ 265

21. Occupancy by one or more households (core topic).................... 265

22. Occupants—number of (core topic) ............................... 266

23. Building—type of (core topic).................................... 266

23.1.Deﬁnition of building ...................................... 266

23.2.Classiﬁcation of buildings by type............................. 267

23.3.Compound .............................................. 268

24. Year or period of construction.................................... 268

25. Dwellings in the building—number of............................. 269

26. Position of dwelling in the building ............................... 269

27. Accessibility to dwelling ........................................ 269

28. Construction material of outer walls (core topic)...................... 269

29. Construction material of ﬂoor and roof............................. 270

30. Elevator—availability of ........................................ 270

31. Farm building ................................................ 271

32. State of repair ................................................ 271

33. Age and sex of the reference person of household (core topic) ............ 271

34. Tenure (core topic)............................................. 272

35. Rental and housing costs........................................ 272

36. Furnished/unfurnished . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

37. Information and communication technology devices—availability of

(core topic)................................................... 273

38. Cars—number of available ...................................... 275

39. Durable household appliances—availability of . . . . . . . . . . . . . . . . . . . . . . . 275

40. Outdoor space—access to ....................................... 275

References ............................................................... 277

Index ................................................................... 281

Page

Introduction

Human capital is the most critical capital for contemporary societies’ well-being and pro-

gress. Providing an accurate and reliable assessment of this capital at small-area, regional and

national levels is of paramount value for evidence-based action by governments, civil societies,

academics, researchers and other stakeholders. e essential purpose of the population and

housing census is to provide that assessment.

Aside from the answer to the question “How many are we?”, there is also a need to

provide an answer to “Who are we?” in terms of age, sex, education, labour force status,

occupation and other crucial characteristics, as well as to “Where do we live?” in terms of

housing, access to water, availability of essential facilities and access to the Internet. e

answers to these questions provide a numerical proﬁle of a nation that is the sine qua non of

evidence-based decision-making at all levels, and are indispensable for monitoring universally

recognized and internationally adopted post-2015 development agenda goals.

A number of countries are capable of generating this numerical proﬁle for small areas

from administrative records or through a combination of data sources. e majority of coun

tries, however, produce detailed statistics on population and housing by conducting a tradi-

tional census, which in principle entails canvassing the entire country, reaching every single

household and collecting information on all individuals within a brief stipulated period of time.

e traditional census is among the most complex and massive exercises a nation

undertakes. It requires mapping the entire country, mobilizing and training an army of

enumerators, conducting a massive public campaign, canvassing all households, collecting

individual information, compiling vast amounts of completed questionnaires and analysing

and disseminating the data.

With the increasingly potent data-processing power available to users of statistics, it

is becoming critical to ensure that census data are exploited as comprehensively as possible.

Detailed small-area statistics are imposing themselves as irreplaceable in pointing to the

segments of everyday life that need to be improved in terms of living conditions, access to

services, adequate infrastructure and fulﬁlment of essential human rights, such as the right

to be registered or the right to vote.

Equally important, a traditional population and housing census is a unique opportu

nity for making statistics visible, both in terms of operations and results. For many people the

census may be the only time that the State reaches them and asks them a question. In addi

tion, successfully conducting a census becomes a matter of national pride for many countries.

Ensuring conﬁdentiality is crucial for the census to succeed. us, it has to be made

clear that the only reason for collecting individual data is for the production of statistics, and

that there will be no dissemination of individual information or any non-statistical linkage

with existing records in other government databases and data collections. Indeed, principle 6

of the Fundamental Principles of Oﬃcial Statistics states: “Individual data collected by sta

tistical agencies for statistical compilation, whether they refer to natural or legal persons, are

to be strictly conﬁdential and used exclusively for statistical purposes.”

Principles and Recommendations for Population and Housing Censuses, Revision 3xvi

e United Nations recommends that all countries or areas of the world produce

detailed population and housing statistics for small-area domains at least once in the period

2015-2024, around the year 2020. For most nations that means conducting a traditional

census, and the present revision of the principles and recommendations for population and

housing censuses thus focuses on the traditional census while also describing in some detail

other approaches for generating reliable small-area statistics on population and housing.

e population and housing census is part of an integrated national statistical sys

tem, which may include other censuses (for example, of agriculture), surveys, registers and

administrative ﬁles. It provides, at regular intervals, the benchmark for population count at

national and local levels. For small geographic areas or subpopulations, it may represent the

only source of information for certain social, demographic and economic characteristics. For

many countries the census also provides a framework to develop sampling frames.

Part one

Essential features and census

methodology

I. Essential roles of the census

1.1. Evidence-based decision-making is a universally recognized paradigm of eﬃcient

management of economic and social aﬀairs and of overall eﬀective governing of societies

today. Generating relevant, accurate and timely statistics is a sine qua non of this model;

producing detailed statistics for small areas and small population groups is its foundation.

e role of the population and housing census is to collect, process and disseminate such

small-area detailed statistics on population, its composition, characteristics, spatial distribu

tion and organization (families and households). Censuses are conducted periodically in the

majority of the countries in the world; they have been promoted internationally since the end

of the nineteenth century, when the International Statistical Congress recommended that all

countries in the world conduct them.

Since 1958, the United Nations has also been actively

promoting the population and housing census by compiling the principles and recommen

dations for population and housing censuses and launching regular decennial worldwide

programmes on population and housing censuses.

1.2. While the roles of the population and housing census are many and will be elaborated

in detail throughout the present revision of Principles and Recommendations for Population

and Housing Censuses, several of the essential roles are listed below:

(a) e population and housing census plays an essential role in public administra

tion. e results of a census are used as a critical reference to ensure equity in

distribution of wealth, government services and representation nationwide by

informing the distribution and allocation of government funds among various

regions and districts for education, health services, delineating electoral districts

at the national and local levels and measuring the impact of industrial develop

ment, to name a few. Establishing a public consensus on priorities would be

almost impossible to achieve if it were not built on census counts. A wide range

of others, including the corporate sector, academia, civil society and individuals,

make use of census outputs.

(b) e census also plays an essential role in all elements of the national statistical

system, including the economic and social components. Census statistics are

used as benchmarks for statistical compilation or as a sampling frame for sam

ple surveys. Today, the national statistical system of almost every country relies

on sample surveys for eﬃcient and reliable data collection, notwithstanding the

emergence of contemporary sources of statistics such as “big data”. Without the

sampling frame and population benchmarks derived from the population and

Report of the Proceedings of the

Fourth Session of the International

Statistics Congress, Held in London

July 16th, 1860, and the Five

Following Days (London, George

Edward Eyre and William Spot-

tiswoode, 1861).

Principles and Recommendations for Population and Housing Censuses, Revision 32

housing census, the national statistical system would face diﬃculties in providing

reliable oﬃcial statistics for use by the government and the general public.

population groups with no or minimum sampling errors. While statistics on

small areas are useful in their own right, they are important because they can be

used to produce statistics on any geographic unit with arbitrary boundaries. For

example, in planning the location of a school, it is necessary to have the data on

the distribution of school-age children by school area, which may not necessarily

correspond to the administrative area units. Similarly, small-area data from the

census can be combined to approximate natural regions (for example, water

catchments or vegetation zones) that do not follow administrative boundaries.

Since census data can be tabulated for any geographic unit, it is possible to pro

vide the required statistics in a remarkably ﬂexible manner. is versatile feature

of the census is also invaluable for use in the private sector for applications such

as business planning and market analyses.

(d) e census results are used as a benchmark for research and analysis. Population

projections are one of the most important analytical outputs based on census

data; future population projections are crucial for all segments of the public and

private sectors.

1.3. In addition to the roles outlined above, it is critically important to produce detailed

statistics for small areas and small population groups as a building block for eﬃcient gov

ernance at all levels. For a vast majority of nations the method of choice for assembling this

building block will be by conducting a population and housing census through universal

and simultaneous individual enumeration of each individual within the nation’s boundaries.

Some nations will adopt alternative approaches; yet, all of these methods must result in

identical outputs: detailed statistics for small areas and small population groups at the same

moment in time.

II. Deﬁnitions and essential features

A. Deﬁnitions

1. Population census

1.4. A population census is the total process of planning, collecting, compiling, evaluating,

disseminating and analysing demographic, economic and social data at the smallest geo

graphic level pertaining, at a speciﬁed time, to all persons in a country or in a well-delimited

part of a country.

1.5. Population is basic to the production and distribution of material wealth. In order to

plan for and implement economic and social development, administrative activity or scientiﬁc

research, it is necessary to have reliable and detailed data on the size, distribution and com

position of population. e population census is a primary source of these basic benchmark

statistics, covering not only the settled population but also homeless persons and nomadic

groups. Data from population censuses should allow presentation and analysis in terms of

statistics on persons and households and for a wide variety of geographic units, ranging from

the country as a whole to individual small localities or city blocks.

3Essential features and census methodology 3

2. Housing census

1.6. A housing census is the total process of planning, collecting, compiling, evaluating,

disseminating and analysing statistical data relating to the number and condition of housing

units and facilities as available to the households pertaining, at a speciﬁed time, to all living

quarters

and occupants thereof in a country or in a well-delimited part of a country.

1.7. e census must provide information on the supply of housing units together with

information on the structural characteristics and facilities that have a bearing upon the main

tenance of privacy and health and the development of normal family living conditions. Suf-

ﬁcient demographic, social and economic data concerning the occupants must be collected

to furnish a description of housing conditions and also to provide basic data for analysing

the causes of housing deﬁciencies and for studying possibilities for remedial action. In this

connection, data obtained as part of the population census, including data on homeless per

sons,

are often used in the presentation and analysis of the results of the housing census, if

both operations are conducted together or there is a link between them.

B. Essential features

1.8. e essential features of population and housing censuses are individual enumeration,

universality within a deﬁned territory, simultaneity, deﬁned periodicity and small-area statistics.

1. Individual enumeration

1.9. e term “census” implies that each individual and each set of living quarters is enu-

merated separately and that the characteristics thereof are separately recorded. Only by this

procedure can the data on the various characteristics be cross-classiﬁed. e requirement of

individual enumeration can be met by the collection of information in the ﬁeld, by the use

of information contained in an appropriate administrative register or set of registers, or by a

combination of these methods.

2. Universality within a deﬁned territory

1.10. e census should cover a precisely deﬁned territory (for example, the entire country

or a well-delimited part of it). e population census should include every person present

and/or residing within its scope, depending upon the type of population count required.

e housing census should include every set of living quarters irrespective of type. is does

not preclude the use of sampling techniques for obtaining data on speciﬁed characteristics,

provided that the sample design is consistent with the size of the areas for which the data are

to be tabulated and the degree of detail in the cross-tabulations to be made.

3. Simultaneity

1.11. Each person and each set of living quarters should be enumerated as of the same well-

deﬁned point in time and the data collected should refer to a well-deﬁned reference period.

e time reference period need not, however, be identical for all of the data collected. For

most of the data, it will be the day of the census; in some instances, it may be a period prior

to the census.

4. Deﬁned periodicity

1.12. Censuses should be taken at regular intervals so that comparable information is made

available in a ﬁxed sequence. A series of censuses makes it possible to appraise the past, accu

For the deﬁnition of living quar-

ters, see paragraph 4.421.

For the deﬁnition of homeless

persons, see paragraph 2.37.

For example, collecting infor-

mation on the core topic of

household deaths in the past 12

months (see paragraph 4.250).

Principles and Recommendations for Population and Housing Censuses, Revision 34

rately describe the present and estimate the future. It is recommended that a national census

be taken at least every 10 years. Some countries may ﬁnd it necessary to carry out censuses

more frequently because of the rapidity of major changes in their population and/or its hous

ing circumstances.

1.13. e census data of any country are of greater value nationally, regionally and interna

tionally if they can be compared with the results of censuses of other countries that were taken

at approximately the same time. erefore, countries should make all eﬀorts to undertake

a census in years ending in “0” or at a time as near to those years as possible. It is obvious,

however, that legal, administrative, ﬁnancial and other considerations often make it inadvis

able for a country to adhere to a standard international pattern in the timing of its censuses.

In ﬁxing a census date, therefore, such national factors should be given greater weight than

the desirability of international simultaneity.

5. Capacity to produce small-area statistics

1.14. e census should produce data on the number and characteristics of the population

and housing units down to the lowest appropriate geographic level, compatible with national

circumstance, and for small population groups, all the while protecting conﬁdentiality of

personal information on each individual.

III. Uses of population and housing censuses

1.15. Population and housing censuses are a principal means of collecting basic population

and housing statistics as part of an integrated programme of data collection and compilation

aimed at providing a comprehensive source of statistical information for economic and social

development planning, administration, assessing conditions in human settlements, research

and commercial and other uses.

1.16. e value of either a population or a housing census is increased if the results can be

employed together with the results of other investigations, as in the use of the census data

as a basis or benchmark for current statistics, and if it can furnish the information needed

for conducting other statistical investigations. It can, for example, provide a statistical frame

for other censuses or sample surveys. e population census is also important in develop

ing the population estimates needed to calculate vital rates from civil registration data (see

paragraphs 1.57-1.59). In addition, these censuses are a major source of data used in oﬃcial

compilations of social indicators, particularly on topics that usually change slowly over time.

e purposes of a continuing coordinated programme of data collection and compilation can

best be served, therefore, if the relationship among the population census, the housing census

and other statistical investigations is considered when census planning is under way and if

provision is made for facilitating the joint use of the census and its results in connection with

such investigations. e use of consistent concepts and deﬁnitions throughout an integrated

programme of data collection and compilation is essential if the advantages of these relation

ships are to be fully realized. Of course, census-type information can also be derived from

population registers and also can be estimated from sample surveys without undertaking a

complete enumeration. ese alternative data sources are presented under “Census methodol

ogy” in paragraphs 1.63-1.119.

1.17. A population and housing census also serves as the logical starting point for work on

the organization and construction of computerized statistical products to serve continuing

national and local needs for data in the intercensal period.

See part three, chapter X, of this

publication.

5Essential features and census methodology 5

1.18. In addition to the statistical value directly obtained from the census results them-

selves, there are further indirect beneﬁts from taking a census, particularly to the organization

responsible for the census, or the national statistical oﬃce. ese beneﬁts include:

(a) Improved skills and experience: varied sets of skills are often required for admin

istering a census that are not necessarily prominent in other parts of the organiza-

tion, such as project management, procurement, and commercial, communica-

tion, human resources and information technology (IT) skills.

(b) Technological advancement: often a census requires new technology to support

complex data collection and processing requirements. ese developments may

be reused for other exercises within the national statistical oﬃce or lead to new

technological developments.

tion, or statistical methods (such as editing and imputation) developed for pro-

cessing census results, can often be reused for other statistical exercises within the

national statistical oﬃce.

(d) Halo eﬀect: the extensive promotion of the census may also have a positive eﬀect,

the “halo eﬀect”, on other surveys, resulting in increases in response rates.

A. Uses of population censuses

1. Uses for policymaking, planning and administrative purposes

1.19. e fundamental purpose of the population census is to provide the facts essential

to national policymaking, planning and administration. Information on the size, distribu

tion and characteristics of a country’s population is essential for describing and assessing

its economic, social and demographic circumstances and for developing sound policies and

programmes aimed at fostering the welfare of a country and its population. e popula

tion census, by providing comparable basic statistics for a country as a whole and for each

administrative unit, locality and small area therein, can make an important contribution to

the overall planning process and the management of national aﬀairs. Counts of the popula

tion overall, or of subgroups within the population, by geographic region are often used for

the distribution of government funding and services. Population censuses in many countries

represent the very foundation of their national statistical systems, with census data providing

important baseline data for policy development and planning, for managing and evaluating

programme activities across a broad range of sectoral applications, and for monitoring overall

development progress. An emerging use for census data is the assessment of good governance

by civil society groups. e performance of a democratically elected government in improving

the welfare of its citizens can be monitored from one census to the other by ordinary citizens

through the widespread and timely dissemination of census results.

1.20. Population censuses serve many programme needs by providing statistical infor

mation on demographic, human settlement, social and economic issues for local, national,

regional and international purposes. For example, population censuses provide basic informa

tion for the preparation of population estimates or projections and detailed demographic and

socioeconomic analysis of the population. e census also provides data for the calculation of

social indicators, particularly those that may be observed infrequently because they measure

phenomena that change slowly over time, and those that are needed for small areas or small

population groups.

The halo eﬀect is a cognitive

bias in which an observer’s

overall impression of a person,

company, brand or product

inﬂuences the observer’s feelings

and thoughts about that entity’s

character or properties. It was

named by psychologist Edward

Thorndike in reference to a per-

son being perceived as having

a halo or aureole. Subsequent

researchers have studied it in

relation to attractiveness and its

bearing on the judicial and edu-

cational systems. The halo eﬀect

is a speciﬁc type of conﬁrmation

bias, wherein positive feelings

in one area cause ambiguous

or neutral traits to be viewed

positively. Edward Thorndike

originally coined the term refer-

ring only to people; however, its

use has been greatly expanded,

especially in the area of brand

marketing.

Principles and Recommendations for Population and Housing Censuses, Revision 36

2. Uses for research purposes

1.21. In addition to serving speciﬁc governmental policy purposes, the population census

provides indispensable data for the scientiﬁc analysis and appraisal of the composition,

distribution and past and prospective growth of the population. e changing patterns of

urban-rural concentration, the development of urbanized areas, the geographic distribution

of the population according to such variables as occupation and education, the changes in

the sex and age structure of the population, and the mortality and fertility diﬀerentials for

various population groups, as well as the economic and social characteristics of the popula

tion and the labour force, are questions of scientiﬁc interest that are of importance both

to research and for solving practical problems of industrial and commercial growth and

management.

3. Uses for business, industry and labour

1.22. In addition to those uses given above, the census has many important uses for individ-

uals and institutions in business, industry and labour. Reliable estimates of consumer demand

for an ever-expanding variety of goods and services depend on accurate information on the

size of the population in subnational areas and its distribution at least by sex and age, since

these characteristics heavily inﬂuence the demand for housing, furnishings, food, clothing,

recreational facilities, medical supplies and so forth. Furthermore, the census can be used to

generate statistics on the size and characteristics of the supply of labour needed for the pro

duction and distribution of such commodities and services in conformity with International

Labour Organization statistical standards.

Such statistics on the local availability of labour

may be important in determining the location and organization of enterprises.

4. Uses for boundary delimitation

1.23. One of the basic administrative uses of census data is to support political and admin-

istrative mapping. Detailed information on the geographic distribution of the population

is indispensable for this purpose. Certain aspects of the legal or administrative status of

territorial divisions may also depend on the size and characteristics of their populations, for

example, whether a previously rural area is now to be declared as urban.

1.24. A compelling use of census data is in the redrawing of electoral constituency bounda

ries in most countries. is is often enshrined in the country’s constitution and provides a legal

basis for census-taking. e current distribution of a country’s population is thereby used to

assign the number of elected oﬃcials who will represent people in the country’s legislature.

5. Use as a sampling frame for surveys

1.25. Population censuses constitute the principal source of records for construction of a

sampling frame for surveys during the intercensal years on many topics, such as the labour

force, fertility and migration histories.

1.26. An essential ingredient of probability sample design is the existence of a complete,

accurate and up-to-date sampling frame. A sampling frame is a list of all (or most) of the N

units in the universe. A sampling frame may be a list of small areas. It may also be a list of

structures, households or persons. e census can be used to construct either type of frame,

or both; indeed, most countries do use their census for such purposes. e census frame is

often the departure point for the design of a household sample survey.

Nineteenth International Confer-

ence of Labour Statisticians,

Resolution Concerning Statistics

of Work, Employment and Labour

underutilization (Geneva, 2013).

7Essential features and census methodology 7

1. 27. It is important to give careful consideration to the construction of a census for sub-

sequent use as a survey sample frame when the census is in the planning stage. e above-

mentioned requirements—accuracy, completeness and up-to-datedness—must be addressed.

is means, for example, that care must be taken to ensure that the entire country is divided

into enumeration areas without any omissions or overlaps, i.e., all land area belongs to one

and only one enumeration area. In terms of their size, enumeration areas are important not

only for the census itself but also for later uses as a potential stage of sampling for surveys;

this feature should therefore also be given due consideration by census planners.

1.28. Maps and prior census information concerning small areas are very important for

devising a good sample plan. e maps are particularly valuable if they unambiguously

indicate boundaries of small areas that can be used as primary or secondary sampling units.

Population and household counts for the enumeration areas, taken from the census, are also

a highly useful ingredient for post-census sample survey design planning. is information

is often used to establish measures of size for the selection of ﬁrst- or second-stage sampling

units, or to help in various stratiﬁcation schemes. Early developments in sampling theory and

methods concentrated on eﬃcient designs and associated estimation techniques for popula

tion totals or means. In consequence, it is generally believed that while censuses covering total

population and housing provide statistical information on a uniform basis for small areas and

subgroups of the population, large sample sizes may have to be considered to produce similar

results for the long-form topics (see paragraph 1.69).

1.29. More recently, however, the methods for analysis of survey data that take into

account the complexity of the sampling design (both sampling and non-sampling errors)

have developed rapidly. erefore, even though sample surveys used alone cannot provide

data for small areas or small population groups, they can be used in combination with a

census on speciﬁc topics. For instance, aggregates of variables recorded on every individual

in the population, which are often used for stratiﬁcation of enumeration areas, may in turn

be used as calibrator or independent variables when models are ﬁtted and used in estimation

of aggregates of variables recorded for samples only, and for small areas not in the sample.

Information users, however, must be made aware whenever results obtained in this fashion

are published. Related techniques have been used in some census operations when checking

information for internal coherence and in some approaches for imputation of missing or

incoherent information.

B. Uses of housing censuses

1. Uses for development of benchmark housing statistics

1.30. e housing census produces benchmark statistics on the current housing situation

and is vital for developing national housing and human settlements programmes. e hous

ing census is also valuable for providing the sampling frame for special housing and related

surveys during the intercensal years.

1.31. Housing benchmark statistics are also critical for emergency planning for response

to natural hazards (such as destructive storms, earthquakes, tsunami and ﬁres), or post-

conﬂict situations. Following such situations, these statistics can be used to estimate the

numbers of people and structures aﬀected, the need for emergency response and reconstruc

tion requirements.

1.32. National statistical authorities would need to develop, from housing censuses, the

sort of benchmark statistics in housing that could be supplemented by current building and

construction statistics and would provide continuous up-to-date information of the hous

Principles and Recommendations for Population and Housing Censuses, Revision 38

ing position needed for the consideration of housing programmes. Since not all the basic

information required to assess housing needs or to formulate housing programmes can be

obtained through a housing census, additional data must be obtained through the popula

tion census, special housing surveys and environmental surveys, and from vital statistics,

economic statistics and so forth; but data obtained from the housing census will constitute

the basic framework within which the estimates are made, indices computed and further

statistical enquiries planned.

1.33. When population and housing censuses are carried out as a single operation or inde

pendently but in a well-coordinated fashion, the combined information provided is of much

higher value, since the essential features of both censuses are interrelated. e information on

housing censuses may be analysed in association with the demographic and socioeconomic

conditions of the occupants and, similarly, the demographic characteristics of the population

may be analysed in association with the data on housing conditions.

2. Uses for the formulation of housing policy and programmes

1.34. e formulation of housing policy and programmes represents one of the principal

uses of housing census data. Housing policy is normally inﬂuenced by social and economic

as well as political considerations, and available factual data concerning the housing situation

provide objective criteria, which are important for policymakers to take into account.

1.35. In most countries, housing programmes encompass both governmental and private

activity. e data derived from a housing census are used by governmental authorities for

making an analysis or diagnosis of the housing situation. Housing conditions are analysed

in quantitative and qualitative terms and data from previous censuses are used to indicate

the changes in the housing situation that have occurred during the intercensal periods; the

housing stock and future housing requirements are estimated and compared with the rates

of dwelling production being attained; and the characteristics of the households in need of

housing are considered in relation to the availability and cost of housing. As part of overall

development plans, such an analysis is necessary for the formulation of national housing

programmes and for their execution.

1.36. Commercial users also study housing census data. ose engaged by the construction

industry, ﬁnancing institutions, and manufacturers of housing ﬁxtures and equipment and

household appliances assess the possible demand for housing and perceive the scope of their

activities within the overall programme.

3. Assessment of the quality of housing

1.37. e materials used for the construction of housing units (roof, walls, ﬂoors) are a

signiﬁcant pointer to the quality of life in diﬀerent parts of a country. Trends indicated by

census data with regard to the type of housing materials can show improvements in the

welfare of the citizenry as the percentage of poor-quality or slum-like housing facilities is

decreased.

C. Relationship between the population census

and the housing census

1.38. An especially close association exists between population censuses and housing cen-

suses. e two censuses may constitute one statistical operation or they may be two separate

9Essential features and census methodology 9

but well-coordinated activities, but in either case they should never be considered completely

independently of each other because essential elements of each census are common to both.

For example, an essential feature of a population census is the identiﬁcation of each occupied

set of living quarters and of the persons living therein, and an essential feature of a housing

census is the collection of information on the characteristics of each set of living quarters in

association with the number and characteristics of its occupants.

1.39. In many countries, the population and housing censuses are taken concurrently, often

with the use of a single schedule. In this way, the information on population and living

quarters can be more readily matched, processing is facilitated and extensive analysis can be

carried out. is also makes it possible to relate to the housing census data the information

on demographic and economic characteristics of each household member that is routinely

collected in the population census.

1.40. e advantages of simultaneous investigation may be oﬀset to some extent by the

additional burden on the respondent and the enumerator resulting from the increased amount

of information that must be collected at one time. In countries where this is likely to be a

serious problem, consideration might be given to collecting data for a limited number of top

ics on the basis of a complete enumeration in the population and housing census, with more

complex data in both ﬁelds being collected on a sample basis only, either concurrently with

or immediately following the full enumeration. Alternatively, consideration might be given

to carrying out the housing census as part of the advance-listing operations of the popula

tion census.

1.41. e relationship between the population census and the housing census will aﬀect the

means by which data on homeless persons are obtained. In the case of simultaneous censuses

of population and housing, data on homeless persons will be obtained as part of the popula

tion census. Where the housing census is carried out independently of the population census,

it may be necessary to try to enumerate homeless persons in the housing census. Information

collected from enumerating homeless persons may reﬂect, among other things, the magnitude

of the housing problem in a given locality.

D. Relationship of population and housing censuses

tointercensal sample surveys

1.42. e rapidity of current changes in the size and other characteristics of populations,

and the demand for additional detailed data on social and economic characteristics of popula

tion and housing characteristics that are not appropriate for collection in a full-scale census

have brought about the need for continuing programmes of intercensal household sampling

surveys to collect current and detailed information on many topics.

1.43. e population and housing census can provide the frame for scientiﬁc sample design

in connection with such surveys (see paragraphs 1.25-1.29); at the same time, it provides

benchmark data for evaluating the reasonableness of the overall survey results as well as a base

against which changes in the characteristics investigated in both enquiries can be measured.

To allow for the comparison of census and survey results, the deﬁnitions and classiﬁcations

employed should be either identical or harmonized, while remaining consistent with the aims

of each investigation. Because of the relative permanence of living quarters, the lists available

from the housing census (with suitable updating) may also provide a convenient frame for

carrying out enquiries dealing with topics other than population and housing.

Designing Household Survey Sam-

ples: Practical Guidelines No.98

(United Nations publication,

Sales No. E.06.XVII.13).

Principles and Recommendations for Population and Housing Censuses, Revision 310

E. Relationship of population and/or housing censuses

to other types of censuses and other statistical

investigations

1. Census of agriculture

1.44. While the population and housing censuses have a close relationship, their relation-

ship with the agricultural census is less well deﬁned. However, as the result of increasing inte-

gration within programmes of data collection, the relationship between the population and

housing census and the agricultural census is now far closer than in the past, and countries

are increasingly looking at new ways to strengthen this relationship.

1.45. One conceptual issue in relating the two censuses is that they use diﬀerent units of

enumeration. e unit of enumeration in the agricultural census is the agricultural holding,

which is the economic unit of agricultural production, while the units of enumeration in the

population census are the household and the individual within the household. In many devel

oping countries, however, there is usually a one-to-one relationship between households with

own-account agricultural production

and agricultural holdings. In these cases the same unit

is enumerated in both types of censuses. For countries where most agricultural production

activities are carried out by households (that is in the household sector), establishing links

between the two censuses is particularly relevant.

1.46. e agricultural census collects various household or individual data for members

of the agricultural holder’s household. e World Programme for the Census of Agriculture

2010

recommends the collection of data on household size and limited data on demographic

characteristics and economic activity of members of the agricultural holder’s household, as well

as some optional data on farm labour, such as persons working as employees on the holding.

Users may ﬁnd some agricultural activity data from the agricultural census more comprehen

sive than from the population census because the latter normally investigates the main work

activity of each person during a short time reference period and this may not identify persons

connected with agricultural activity on a seasonal basis or as a secondary activity. On the other

hand, the population census provides data on all persons working in agriculture, including

as paid employees. Such information is not available from the agricultural census, which

only covers households with own-account agricultural production. To get a complete picture,

agricultural data users will need both agricultural census data and population census data.

1.47. In planning the population and housing census, every opportunity for developing

the relationship between this census and the agricultural census should be explored. is

can take several forms. Deﬁnitions used in the population and housing censuses should be

compatible with those used in the agricultural census so that meaningful comparisons can

be made between the two data sets. e population and housing census can also be of use in

the preparation of the agricultural census, such as in the demarcation of enumeration areas,

the preparation of the frame for the agricultural census or, if applicable, the sample design.

1.48. In planning the national census programme, serious consideration should be given

to the possibility of collecting key agricultural information as part of the population and

housing census exercise that would facilitate the preparation of the frame of agricultural

holdings in the household sector for a subsequent agricultural census. is could be done as

part of the pre-census cartographic work and/or listing exercise or by adding a few questions

to the census questionnaire (as elaborated in paragraphs 4.387-4.396). In the latter case,

additional items at the household level could be included to identify whether any member

of the household is engaged in own-account agricultural production activities. It may also

be useful to collect additional data at the individual person level to identify persons involved

in agricultural production activities during a longer period, such as a year. Information on

An agricultural holding is an

economic unit of agricultural

production under single man-

agement comprising all livestock

kept and all land used wholly or

partly for agricultural production

purposes, without regard to title,

legal form or size.

That is, households with mem-

bers engaged in agricultural

activities as self-employed work-

ers or as own-use producers.

Food and Agriculture Organiza-

tion of the United Nations,

A System of Integrated Agricultural

Censuses and Surveys, Volume 1:

World Programme for the Census

of Agriculture 2010, Statistical

Development Series No. 11

(Rome, 2005).

11Essential features and census methodology 11

occupation or industry and status in employment, and participation in own-use production

of agricultural goods where relevant, could together facilitate identiﬁcation of households

with own-account agricultural production. Where countries choose to adopt this approach

of using the population and housing census to establish a frame for the agricultural census,

the agricultural census should be synchronized with the population and housing census and

conducted as soon as possible after the population and housing census, while the frame is

still up to date. is approach is detailed in the Guidelines for Linking Population and Housing

Censuses with Agricultural Censuses with Selected Country Practices.

1.49. Linking population and agricultural census data can bring many beneﬁts. is could

add considerable analytical value to data sets from both censuses and save on data collection

costs. Many of the demographic and activity status data collected in the population census

are also collected in the agricultural census. If data from the two censuses could be linked,

it would no longer be necessary to collect these data again in the agricultural census, while

still allowing for comprehensive cross-tabulations.

1.50. A few countries conduct the data collection for the population and agricultural cen

suses as a joint ﬁeld operation. Normally, each census retains its separate identity and uses its

own questionnaire, but ﬁeld operations are synchronized so that the two data collections can

be done at the same time by the same enumerators. Occasionally, the two censuses are merged

into one. is may have a number of advantages; however, as this is an increasingly complex

operation, its impact on ﬁeld operations and data quality needs to be carefully considered.

2. Census of establishments

1.51. Although the collection of information on industrial and commercial establishments

does not constitute a part of the population census, the information that is collected from

employers and own-account workers regarding the economic units they operate, such as the

kind of economic activity and the size of the unit, can be used for preparing listings of the

proprietors of such establishments. ey can also be used to prepare listings of the establish

ments themselves, if information is requested on their location or when the establishments

are located within the living quarters (or dwellings). Experience shows that these listings can

be used in a subsequent census of establishments or for supplementing the registers of estab

lishments maintained by most countries and utilized as a list-based or area-based sampling

frame for their establishment surveys.

1.52. Many business registers cover only establishments with ﬁxed visible premises in which

more than some minimum of persons (usually 5 or 10) are employed. In these cases, the popu

lation census can be used to collect basic information (such as kind of activity and size) on

those establishments with employment below the minimum number of persons by identify

ing the self-employed persons that operate them. However, special care should be taken in the

choice of the unit of enumeration to ensure that there is no double counting of establishments.

1.53. When the information from the population census is to be used to construct a list-

based sample frame, it is essential that the information from the population census be avail

able and used shortly after the enumeration is carried out because this information can

quickly become outdated. is requirement is less imperative when the information is to be

used to construct an area-based sample frame.

1.54. e population census information needed for these purposes is the status in employ

ment, in order to identify employers and own-account workers. For this subset of workers,

information needs to be collected on the number of establishments operated, and for each

of these, the kind of economic activity, the name and address of the establishment (if any),

the number of workers engaged (including contributing family workers and employees) and

Food and Agriculture Organiza-

tion of the United Nations and

the United Nations Population

Fund, Guidelines for Linking

Population and Housing Censuses

with Agricultural Censuses with

Selected Country Practices (Rome,

2012).

Principles and Recommendations for Population and Housing Censuses, Revision 312

whether the establishment is operated in partnership with other persons. If all of this informa-

tion appears in the census questionnaire, the number of small establishments can be extracted

from the schedule or from the processing documents after the enumeration.

3. Census of buildings

1.55. In certain circumstances, it may be necessary, as part of the housing census operations,

to enquire whether or not all buildings (both residential and non-residential) are occupied.

us, it may be convenient to record basic information for all buildings at the time of the

housing census, even though detailed data may be collected only for those in which housing

units or other sets of living quarters are located. e comprehensive list thus obtained some

times provides the basis for a census of buildings, carried out concurrently with, or subsequent

to, the housing census, or it may provide for the identiﬁcation of special types of buildings

signiﬁcant for other enquiries, such as the census of establishments or the census of schools.

If a listing of households is to be carried out before the actual enumeration, this would be

most ideal for carrying out such an exercise.

4. System of current housing statistics

1.56. Current housing statistics refer to housing activity. ey reﬂect the number of dwell-

ings constructed and certain related information such as value, number of rooms, ﬂoor space,

and so forth, as well as number of dwellings destroyed or demolished. ese data are usually

obtained from a system of data collection based on the administrative procedures required in

connection with the activity in question. For example, construction statistics may be derived

from permits issued for the construction of dwellings, from records of dwelling starts or com

pletions, or from certiﬁcates of occupancy. Statistics on dwellings destroyed may be obtained

from the records maintained for the levying of rates and the collection of taxes. Compiled

monthly or quarterly, current housing statistics reﬂect changes in the housing inventory and,

although they may serve other purposes, they are also used to update the benchmark data

obtained from housing censuses.

5. Civil registration and vital statistics

1.57. Population census data serve as denominators for the computation of vital rates, espe-

cially rates speciﬁc for characteristics normally investigated only at the time of the census.

Conversely, census results, time adjusted by vital and migration statistics, can provide esti

mates of the future size, distribution and other characteristics of the population of the total

country and subnational areas. Furthermore, census data on fertility can provide a bench

mark check on the reliability of current birth statistics, and vice versa. It is consequently

desirable that procedures for the collection of population census data, vital statistics and

migration statistics be closely coordinated with regard to coverage, concepts, deﬁnitions,

classiﬁcations and tabulations.

1.58. It may be noted that some countries have linked individual census returns for infants

less than 1 year of age with birth registration reports for the year preceding the census date as

a means of checking on the completeness of one or the other type of investigation. Linkage of

death reports with census returns has been used to compare the information on characteristics

of the deceased as reported in the two sources.

While the many problems posed in the past

by the one-to-one matching of two types of records have not been entirely solved, their sever

ity has been mitigated by developments in computer technology. Before undertaking either

of the procedures, however, countries should consider carefully the possible advantages of

using household sample survey returns rather than census returns in the operation. Moreover,

An elaboration of comparison

between census and vital

statistics is provided in Principles

and Recommendations for a

Vital Statistics System, Revision3

( UnitedNations publication,

Sales No. E.13.XVII.10), paras.595-

597).

13Essential features and census methodology 13

such operations have to be carried out in complete accord with national laws and policies

governing the conﬁdentiality of information obtained in the census if public conﬁdence in

the census is to be maintained.

1.59. In the establishment of a vital registration system, census results on the geographic

distribution of the population can be useful in the consideration of appropriate locations for

registration oﬃces.

6. Administrative data sets

1.60. ere is an increasing availability of a range of government and private data sets con-

taining information on the persons or the households within a country. e utility of these

data sets for statistical analysis is usually limited by their lack of population coverage, data

accuracy or range of characteristics. e linkage of these data sets with the census ﬁle, with

its complete coverage of the persons and households, can provide the ability to create new

insights and new statistical products to leverage more value from the census.

1.61. Administrative data can replace census data—for example, in some countries income

data from the taxation or revenue department can replace the need to directly collect those

data in the census. Administrative data can also extend census data—for example, census data

can be linked with visa information or health information to extend the census data set into

areas that may be too sensitive to collect on the census form, or with past education data to

analyse longitudinally the impact of education on labour force outcomes. Administrative data

can also replace missing data—for example, in one country health records have been used to

impute the count and characteristics of usual residents that were non-responding during the

census enumeration period.

1.62. As described above in paragraph 1.58, linkage operations should be undertaken with

caution, ensuring not only that all national laws are met but also that the trust of the public

in the census and the statistical systems is maintained.

IV. Census methodology

1.63. Summarizing the experiences of the previous population and housing census round,

it became evident that a number of countries were exploring the use of alternative meth

odologies with respect to the traditional census for producing census statistics. e use of

registers—primarily population registers—in combination with other sources is being con

sidered in a number of countries for the purpose of producing detailed small-area statistics

on population and housing, as well as the application of continuous survey methodology for

the same purpose. Furthermore, these alternatives to the traditional method of conducting

population and housing censuses are becoming more diverse in terms of developing combi

nations of various data collection methods (see paragraph 1.95), and it is thus a challenge to

summarize and categorize them using generally accepted data source methodologies.

1.64. It should be noted that most countries are expected to continue using the traditional

census approach—soliciting information from each household in a country—in the 2020

round of censuses,

while at the same time it is anticipated that increasing numbers of countries

will intend to use alternative methodologies. ere are quite a few reasons for exploring alterna

tive approaches, and the following presents a sample: (a) the need to produce more frequent and

timely statistics; (b) budgetary limitations for census taking; (c) reluctance of the population

to participate in the census; and (d) increased technical capacities to manipulate data sources.

The 2010 round of population

and housing censuses was

inaugurated by the Economic

and Social Council of the

UnitedNations and covered the

period from 2005 until 2014.

The 2020 round of censuses cov-

ers the decade 2015-2024.

Principles and Recommendations for Population and Housing Censuses, Revision 314

1.65. is section aims to brieﬂy elaborate on possible methodologies for conducting cen-

suses based on the recent experiences of countries. e section also describes the necessary

conditions for using a speciﬁc methodology, its advantages and disadvantages, and its impli

cations for the content and administration of the census. It should be kept in mind that

countries using a speciﬁc census methodology might have signiﬁcant diﬀerences in imple

mentation of the methodology, arising from diﬀering country conditions and expectations.

Regardless of the approach, the crucial principle of providing detailed statistics at the lowest

geographic level remains of paramount importance.

1.66. e various census methodologies are represented in a matrix in table 1, where the

rows describe data collection through ﬁeld enumeration and the columns represent use of

administrative or population registers as census data sources. e matrix presents only those

options that either have been used or are likely to be used by countries and does not present

all possible combinations, including theoretical ones that have yet to be tested by any country.

1. 67. e diﬀerent approaches are explained in table 2.

First, the full ﬁeld enumeration

and the register-based census are presented; then the combined methodologies are described.

Alternative approaches have been adopted in diﬀerent ways by diﬀerent countries, depending

on national preferences and practices and the availability of appropriate data sources.

1.68. e columns in the matrix present diﬀerent types of registers: administrative registers,

statistical registers and base registers. Administrative registers are registers that are created

and used mainly for administrative purposes outside the national statistical authorities. An

administrative register will be edited, corrected and perhaps imputed into a statistical register

inside a statistical institute and can then be used for statistical purposes. A statistical register

can also be established inside a statistical institute for statistical purposes; one example could

be a register of occupations that in many cases does not have any administrative purposes.

Base registers are registers, such as the population register, dwelling register or enterprise reg

ister, that create a population base for individuals, dwellings and enterprises. Other registers

will then be matched with a base register. e household register will be created by combining

the population and dwelling registers.

Table 1.

Overview of census-taking methodological approaches

Type of data collection Use of registers as census data sources

No registers (fully ﬁeld

enumeration based or

sample surveys)

Base registers

(individuals, households,

dwellings)

Integrated

administrative sources

Full ﬁeld enumeration Full ﬁeld enumeration only

(traditional census)

Base registers and full ﬁeld

enumeration

Integrated administrative

sources and full ﬁeld

enumeration

Rolling surveys

(continuous surveys)

Full ﬁeld enumeration

and rolling surveys

n.a. n.a.

Rolling census

Ad hoc sample surveys n.a. Base registers and ad hoc

sample surveys

Integrated administrative

sources and ad hoc sample

surveys

Existing sample surveys n.a. Base registers and existing

sample surveys

Integrated administrative

sources and existing

sample surveys

No ﬁeld enumeration

(fully register based)

n.a. n.a. Fully register based

For more details see

UnitedNations Economic Com-

mission for Europe, Using Admin-

istrative and Secondary Sources

for Oﬃcial Statistics: A Handbook

of Principles and Practices, ECE/

CES/13 (Geneva, 2011); and Reg-

ister-based Statistics in the Nordic

Countries: Review of Best Practices

with Focus on Population and

Social Statistics ( UnitedNations

publication, Sales No. E.07.II.E.11).

In a fully ﬁeld enumeration-

based census, data from regis-

ters are not used as a census data

source, even though registers

may be used as a frame and to

support ﬁeld operations.

Integrated administrative

sources with information

on business, tax, education,

employment and other relevant

registers.

15Essential features and census methodology 15

Table 2.

Descriptions of approaches

Approach Description

Full ﬁeld enumeration

(traditional census) or full

ﬁeld enumeration and

rolling surveys

Information on census topics concerning individuals and households is collected by census

questionnaire directly from respondents using enumerators or other modes of data collec-

tion (e.g. telephone interview, mail out/mail back, Internet), or by applying a combination of

diﬀerent modes of data collection. In a traditional census, full ﬁeld enumeration may include

an in-built ad hoc survey by use of the long form or can be combined with a rolling survey. It

is common that a short form is used together with a long form. Both forms are utilized dur-

ing the same time frame of the census. While the long form estimates are not based on full

coverage, they are regarded as census output. Through modelling, the full ﬁeld enumera-

tion with the continuous cumulative survey is used to generate yearly (or other interval)

estimates of detailed characteristics for diﬀerent geographic levels. With this approach, the

sample can be cumulated over time to produce statistics at the lowest levels of geographic

detail to provide more frequent and relevant data.

Rolling census Information on individuals and households is collected through a continuous cumulative

survey covering the whole country over a period of time (generally years), rather than a

particular day or short period of enumeration. The two main parameters of a rolling census

are the length of the period of enumeration (which is linked to the frequency of updates

required) and the sampling rate (which depends on the geographic levels required for

dissemination purposes).

Combined methodology Information on individuals and households is collected by combining data collected from

one or more surveys or full ﬁeld enumeration with administrative or statistical registers.

Data from registers are employed not only as a frame or to support ﬁeld operations,

but directly as a data source for some census information. In some cases, register data

are used to preﬁll the questionnaires to be veriﬁed or corrected during data collection.

Adhoc sample surveys are used to provide information on census topics not available from

administrative sources or to adjust data that are of poor quality in registers.

Base register and exist-

ing sample surveys or

integrated administra-

tive sources and existing

samples survey

Information on individuals and households is collected from existing administrative

sources, namely diﬀerent kinds of registers, of which the following are of primary impor-

tance: individuals, households and dwellings. These are linked at the individual level with

information from existing sample surveys. No ﬁeld data collection will take place. Existing

sample surveys include intercensal sample surveys on diﬀerent topics, such as the labour

force survey and the living standards survey.

Fully register based Information on individuals and households is collected from existing administrative

sources, namely diﬀerent types of registers, of which the following are of primary impor-

tance: individuals, households and dwellings. These are linked at the individual level with

information taken from other administrative or statistical sources, such as business, tax,

education, employment and other relevant registers.

A. Full ﬁeld enumeration (traditional census)

1.69. e full ﬁeld enumeration or traditional approach comprises a complex operation

of actively collecting information from individuals and households on a range of topics at a

speciﬁed time, accompanied by the compilation, evaluation, analysis and dissemination of

demographic, economic and social data pertaining to a country or a well-delimited part of

the country. Members of the public respond to a census questionnaire, or interviewers are

deployed to collect information from respondents. For interviewer-based censuses, enumera

tors assigned to diﬀerent enumeration areas cover all households and persons in the enumera-

tion area during a speciﬁed and usually short period of time in order to meet the require-

ments of universality and simultaneity. Either a single long form is universally canvassed, or

a combination of short and long forms used. In the latter case, the short form contains only

questions intended for universal coverage, while the long form is used to collect information

from only a sample of households and population. is form usually contains detailed ques

tions on a particular topic in addition to covering complex topics such as fertility. Both forms

are utilized during the same time frame of the census. While the long form estimates are not

Principles and Recommendations for Population and Housing Censuses, Revision 316

based on full coverage, they are regarded as census output. Overburdening the census form

is likely to adversely aﬀect response rates and the quality of data.

1.70. A variant of this approach consists in modelling the full ﬁeld enumeration with a

continuous cumulative survey in order to generate yearly (or at other intervals) estimates of

detailed characteristics of population and housing. e primary advantage of this approach is

to provide more frequent and relevant data on population and housing than would be avail

able when a census is conducted only once a decade. However, such a programme might be

costly and technically diﬃcult, as it requires a multi-year round of comprehensive planning,

development and testing.

1.71. As various methods can be used for collecting the data, including a mailed or dropped-

oﬀ questionnaire, the telephone, the Internet, personal visit follow-up, or a combination of

such methods, countries employing the traditional design may utilize very diﬀerent collection

approaches in doing so.

1.72. e traditional census has merit in providing a snapshot of the entire population at a

speciﬁed period and data for small geographic domains. In that sense, the traditional census

is perhaps unique in nature. is approach is particularly suitable for countries requiring

population numbers by various social and economic characteristics simultaneously for all

geographic levels to meet the needs of planning and the allocation of funds. e delimitation

of electoral boundaries requires simultaneity, and for that reason also the traditional approach

may be more appropriate. But at the same time, traditional censuses have been singled out

as the most elaborate, complex and costly data collection activity that national statistical

authorities undertake. In addition to costs, this complex task requires full awareness and

agreement of the public to participate in it.

Necessary conditions

1.73. It is essential to have national legislation for conducting the population and hous

ing census to ensure conﬁdentiality, transparency and the cooperation of the population.

A permanent central census organization, which may or may not be part of the statistical

oﬃce, needs to exist in the country, which can be expanded during the time of the census.

Since a traditional census requires substantial resources, suﬃcient funding for a ﬁeld opera

tion covering the entire country and subsequent data processing needs to be ensured. Other

conditions necessary for this approach are the support of and general acceptance by the public

to participate in the enumeration, and trust towards the statistical oﬃce or census agency.

Advantages and disadvantages

1.74. e two biggest advantages of a traditional census are comprehensiveness of cover

age and simultaneity. Another major advantage is the ﬂexibility in deciding the topics to be

covered and design of the questionnaire. ere is lesser need for complex data adjustment

since processing of raw data provides all inputs. e census frame becomes the base for all

subsequent sampling frames. Finally, the focused and time-bound nature of the ﬁeld opera

tion implies that the data collection is ﬁnished in a short period and does not require long-

term or constant monitoring.

1.75. One of the biggest disadvantages of a traditional census is its cost and administrative

complexity. Another disadvantage is that it has a very long processing time. Also, since it can

be conducted only after 5- or 10-year intervals, data tend to become outdated. e burden

on respondents can be considered a disadvantage, especially in countries where participation

in the enumeration is declining. Finally, many countries experience increasing diﬃculties in

enumerating speciﬁc population groups, such as persons with high mobility or with multiple

residences, or who are diﬃcult to reach for other reasons.

17Essential features and census methodology 17

Some considerations for census taking and content

1.76. Very precise planning is required for every stage of census taking in the traditional

approach, due to the sheer volume of work and overlapping time frames. e recruitment

and training of a large number of census takers adds to cost and complexity. Involvement of

administrative machinery at the central, provincial and local levels is essential for successful

ﬁeld operations.

1.77. Since the data obtained in the traditional method are respondent- and enumerator-

based, there is scope for error in canvassing the questions and in the quality of response. is,

however, can be minimized through proper design of the questionnaire, eﬀective training

and wide publicity.

1.78. Data can be provided for every administrative level subject to privacy and conﬁden

tiality considerations, which may not always be possible with other methods if some parts of

the data collection are based on sample surveys.

1.79. Essential features of a population and housing census are fully satisﬁed with the tra

ditional census method.

B. Register-based census

1.80. e concept of producing census-like results based on registers developed in the 2000

round of censuses, although it has been debated and tested to various degrees since the 1970s,

and several countries succeeded in using this approach to generate census data in the 1990

round of censuses. e philosophy underlying this concept is to take advantage of existing

administrative sources, namely diﬀerent kinds of registers on individuals, households and

dwellings. ese registers are linked at the individual record level with information held on

business, tax, education, employment and other relevant registers. While it is theoretically

possible to link records on the basis of the name and other unique details of the individuals,

the existence of a unique identiﬁcation number for each individual, household and dwelling

allows a much more eﬀective and reliable linkage of records from diﬀerent registers.

1.81. Administrative registers are produced on the basis of administrative processes to

collect information on units (persons and housing units) and variables that are deﬁned by

administrative rules and demands in a country. Although the content and process of registers

would diﬀer from one country to another, the types of the registers are usually very similar.

e following provides deﬁnitions of the main concepts used in the system of administrative

registers.

(a) A register is deﬁned as systematic collection of unit-level data organized in such

a way that updating is possible. Updating is the processing of identiﬁable infor

mation with the purpose of establishing, updating, correcting or extending the

(b) Administrative registers are registers primarily used in an administrative informa

tion system. is means that the registers are used in the production of goods and

services in public or private institutions or companies, or that the information is

a result of such production. Administrative registers used for statistical purposes

are normally operated by the State or jointly by local authorities, but registers

operated by private organizations are also used.

e function is to keep stock of the population and to maintain identiﬁcation

information. Statistical base registers are based on the corresponding adminis

Nordic Countries: Review of

Best Practices with Focus on

Population and Social Statistics

(United Nations publication,

Sales No.E.07.II.E.11).

Principles and Recommendations for Population and Housing Censuses, Revision 318

trative registers. eir principal tasks are to deﬁne important populations and

contain links to other base registers.

(d) Specialized registers are registers that, unlike base registers, serve one speciﬁc pur

pose or a clearly deﬁned group of purposes. Specialized registers often receive

information on the population and some basic data from a base register, but

supply other data themselves (such as the register of vehicles).

(e) Statistical registers are created by processing data from administrative registers for

statistical purposes. A statistical register could be based on one or several admin

istrative registers. Statistical registers are also referred to as secondary registers.

1.82. e process involves collecting information on the characteristics of individuals,

which has been provided to an administrative register for non-statistical purposes. To be

eﬀective, access to administrative data for statistical purposes must be given by law or by

agreement, providing the capability to (a) transfer the data as individual records to the sta

tistical database; or (b) temporarily link the registers to form a proxy register for statistical

purposes.

1.83. Administrative registers are maintained primarily for administrative purposes. Units

and variables of administrative data are described according to administrative rules and

demands. Before a register is used for census purposes, the suitability of its data in terms of

deﬁnitions, concepts, content, reference date, accuracy and other criteria should be statisti

cally tested by comparing them with previous census and survey results, and conducting qual-

ity and compatibility surveys. A pilot census may be used for this purpose. Some backbone

registers and administrative sources are:

(a) Population register (base—usually covers births, deaths, marriage and migration);

(b) Buildings and dwelling or address register (base);

(d) Taxation register;

(e) Employment register;

(f ) Pension register;

(g) Social welfare register;

(h) Jobseeker register;

(i) Student register.

1.84. All persons within the deﬁned territory who meet the register’s rules are enumer

ated. In concept, the enumeration is taken from a population register in which the ﬁelds for

diﬀerent census attributes are populated from subsidiary registers relating to speciﬁc topics.

Information is extracted from the register as it reﬂects the situation of individuals at the

predeﬁned census reference date. e timing of the census extraction may require careful

thought where register update cycles vary. Registration delays and administrative delays in

updating between regional and national databases can otherwise have a serious impact on

the quality of the output.

1. Register source with existing sample survey

1.85. A special case of register-based census is when population and/or integrated admin-

istrative registers are combined with existing sample survey(s). Diﬀerent data sources are

integrated as part of a “virtual census”

process. e data for the census exercise are derived

from many types of registers and surveys, covering diﬀerent population groups throughout

the country and its subregions. Compared to conventional census methods, this process is

The term virtual census originated

in the Netherlands, where it was

ﬁrst developed, and here it refers

to that speciﬁc methodology.

19Essential features and census methodology 19

lower in cost and staﬀ requirements, and uses more frequently updated data sources. More

signiﬁcantly, by combining data that are already available from other sources, the virtual

census makes no additional respondent burden, increasing its public acceptability.

1.86. A weakness of the use of sample data within the census exercise is that for the variables

derived from the sample surveys the sample size may not be suﬃcient to oﬀer the geographi

cally detailed outputs that are an essential feature of the census. Importantly though, the use

of data from existing regular surveys will often mean that time series of data are available. By

combining samples for several survey exercises, it may be possible to produce reliable estimates

for small geographic areas.

1.87. However, the use of existing surveys does present a number of problems compared to

the use of ad hoc surveys. e timing, content, statistical deﬁnitions and sampling approaches

used in an existing survey may not be appropriate to allow the data to be readily combined

with data from the administrative source(s). For example, many major household surveys are

not designed to cover persons living in institutional households (such as student accommo

dation, hospitals, prisons and military establishments), meaning that an additional source of

information is needed for these persons.

2. Necessary conditions

1.88. Among the essential preconditions to conduct a register-based census is that the coun-

try should have:

(a) A national legislation providing for the creation of a population register and

permission to use the data contained in it for statistical purposes;

(b) An established central population register;

(d) Comprehensive geographic coverage in the register;

(e) An eﬀective system of continuous updating of the population register.

With regard to other administrative registers used, the following are essential:

(a) Access to data in the various registers should be allowed through legislation;

(b) e concepts and deﬁnitions used in the various registers should be harmonized;

facilitate proper linking of data;

(d) Quality and consistency checks should be conducted to verify the suitability of

the data contained in various registers.

3. Advantages and disadvantages

1.89. e primary advantages of a register-based approach are reduced costs and greater

frequency of data. However, establishing and maintaining administrative registers involve

higher costs than the census alone may justify. e need for the register will largely be based

on its contribution to more reliable and eﬃcient administration. e use for statistics may be

valuable but is likely to be a secondary consideration.

1.90. Certain potential drawbacks with the use of administrative data sources also need to

be taken into account. One limitation is that the scope of statistical topics, key deﬁnitions

and, indeed, the population base of the exercise depend on the information that can be com

piled from the available registers. ese, in turn, will be based on the underlying administra-

tive purpose and procedures of the registers. In addition, it is common for national legislation

Principles and Recommendations for Population and Housing Censuses, Revision 320

to restrict or prevent the use of administrative registers for other purposes, including the

production of statistics. is may impose restrictions with respect to the characteristics that

are available for description, and may also undermine international comparability. When a

registered data item is changed, new or updated information is not always registered imme

diately. In certain cases, new or updated information may not be registered at all. Where this

occurs, the register information does not accurately reﬂect real circumstances.

4. Some considerations for census taking and content

1.91. Administrative registers can, depending on content and quality, be used in all phases

of census-taking. In principle, where greater amounts of information can be obtained from

administrative sources, the production of census-type statistics will be faster, cheaper and

more complete. e most complete use of registers will be where all core, and in some coun

tries non-core, census topics can be based on register information. It is possible to improve the

quality of data collected through the administrative register by conducting a sample survey

or surveys. e sample survey(s) may either use the register as a sampling frame, or else be

completely independent of the register.

1.92. e use of register data may reduce the ﬂexibility of the census exercise in terms of the

variables that are available and their deﬁnitions. It may be diﬃcult to change the variables as

these are deﬁned in line with administrative priorities. A signiﬁcant potential risk for the suc

cess of the census exercise is that the administrative source will often be outside the control of

the statistical authority. e inﬂuence of the statistical authority over the administrative source

can be very limited. e content and availability of the administrative source may change at

relatively short notice and without reference to statistical needs. For example, a change in

taxation legislation may mean that a key administrative register may no longer collect infor

mation needed for the census. is risk can be minimized by establishing close and regular

communication between the statistical authority and the owners of the administrative sources.

1.93. In practice, only persons legally present in the various registers would get covered

through this approach. For example, unregistered births, deaths or marriages, illegal immi

grants, homeless persons, nomadic or ﬂoating populations, persons involved in illegal activi-

ties, etc., are not likely to be recorded in any such administrative register. On the other hand,

registers may include persons who are actually not living (any longer) in the country, for

example persons who emigrated but were not cancelled from the registers.

1.94. Summing up, subject to the caveats mentioned in the paragraphs above, the feature

of individual enumeration is satisﬁed in this approach as separate information is collected

regarding the characteristics of each individual. As regards “universality within a deﬁned

territory”, this criterion is satisﬁed as the enumeration is taken from a population register

in which the ﬁelds for attributes are populated from subsidiary registers relating to speciﬁc

topics. With regard to “simultaneity”, the timing of the census extraction may require care

ful thought where register update cycles vary. With respect to “periodicity”, this approach

allows extraction at desired frequencies, including “at least once in 10 years”, noting again the

need to manage the updating cycles for the registers. Finally, in most cases, the requirement

in terms of producing small-area statistics is largely met, as the information in the registers

allows for such aggregates to be generated.

21Essential features and census methodology 21

C. Combined methodologies

1.95. In recent years, it has been observed in a number of countries that:

(a) e quality of the administrative registers is relatively good (at least for certain

key census variables);

(b) Information for some census topics is not available in the administrative registers

or the quality is not suﬃciently high;

diﬃcult to enumerate), are becoming more sensitive to the handling of personal

information, and possibly more reluctant to cooperate with the statistical oﬃce

or more diﬃcult to enumerate due to their high mobility or other reasons.

1.96. In these cases, a combined census that uses register(s) and questionnaire(s) could be

an option. Essentially, the combined methodology makes use of registers relevant to a census,

complemented by surveys or complete enumeration. e use of survey and enumeration data

is intended to:

(a) Improve the accuracy of the population counts;

(b) Provide information for census variables that cannot be reliably based on admin

istrative data;

tive sources;

(d) Add additional variables to the census;

(e) Be a linking frame in order to bring together diﬀerent sources.

1.97. Information on individuals, households and dwellings is collected by combining data

from registers with data collected from one or more surveys. Data collection may be based

on full ﬁeld enumeration, an ad hoc sample and rolling survey methods. Data from registers

are employed not only as a sampling frame or to support ﬁeld operations, but also directly

as the data source for some census information. In a case where registers are used along with

total enumeration, data from registers may be preﬁlled in questionnaires, and respondents

may be asked to check, update and conﬁrm their details. Other questions relating to ﬁelds

not available in the registers may also be canvassed during this exercise. In the case of new

individuals, households or dwellings that do not feature in the register, all ﬁelds of informa

tion that are required for the register and the census are to be canvassed afresh. When registers

are used along with sample surveys (ad hoc sample or rolling surveys), some census tables may

be produced entirely from the information available on the register(s), while for other census

tables, information from the survey(s), duly weighted to the population totals, could be used.

e surveys would also serve to evaluate the accuracy of the register counts.

1. Necessary conditions

1.98. e option of a register-based census with sample surveys can be adopted only if all

necessary census information is available from the various administrative or survey sources,

and it is possible to link the information from the diﬀerent sources at the record level. During

the process of integrating individual records, care should be taken to check the accuracy of

the data and remove inconsistencies prior to the production of statistical outputs.

1.99. e data sources would include veriﬁed and accurate personal information (name,

ID number, date of birth, sex, marital status, family structure, etc.) and a dwelling register.

In an ideal situation, a “base” register can be envisaged, to include uniﬁed identity codes for

both people and address components in order to link more eﬃciently the related register and

survey data. e link between persons and their dwellings is equally important, giving the

Principles and Recommendations for Population and Housing Censuses, Revision 322

household unit. Other administrative data sources include tax ﬁles, social security ﬁles, public

records of unemployed and registers of educational qualiﬁcations. It is preferable to have a

centralized base register. If this is not available, regional registers will need to be consolidated.

2. Advantages and disadvantages

1.100. e register-based census combined with full enumeration or surveys oﬀers several

advantages:

(a) It can be much cheaper than a traditional census with a full enumeration collect

ing all census items from the whole population;

(b) It will reduce the burden of enumerators and respondents;

(d) It should be possible to correct the survey data for diﬀering levels of non-response

in diﬀerent population groups.

1.101. Micro-integrated data might be expected to provide very reliable results, because

they are based on a maximum amount of information. e coverage of subpopulations may

be more reliable because when data are missing in one source, another source may be used.

Another advantage of micro-integration is that there will be less reason for confusion among

statistics users. For example, there will be one ﬁgure on each socioeconomic phenomenon,

instead of several diﬀerent ﬁgures depending on which sources have been used.

1.102. A disadvantage is that it involves more work to produce the tables from the sample

survey microdata, as weighting problems may arise. As the combined census may lack the

high public proﬁle and publicity of a traditional census, there may be less interest in and use

of the census results, as there is no longer a single census event to attract public attention.

Other potential disadvantages may be a lack of transparency (no one external to the process

may be able to reproduce the information) and data quality.

3. Some considerations for census taking and content

1.103. Data validation, processing and dissemination may be more complicated, as this

approach involves both total counts based on the register and sample data from surveys.

In addition, as some variables are based only on sample data, it may be impossible to meet

the level of statistical and geographic detail required in some tables. On the other hand, the

possibilities of reducing cost and response burden provide a very strong reason to adopt this

approach.

1.104. Some of the required variables will need to be constructed from diﬀerent sources.

e census results obtained may diﬀer to some extent from those that would be obtained

from a full enumeration covering all census topics. is may have a negative impact on the

comparability of results between countries and over time. An advantage of registers is that,

in eﬀect, they oﬀer complete coverage subject to the quality of the data contained (see also

paragraph 1.93). It is preferable that statistical authorities make full use of the register data

that are available.

1.105. For the combined census method, a number of diﬀerent methods can be used to

collect information, including paper, Internet, handheld devices and telephone interviews.

Electronic devices have important advantages that inﬂuence the quality of the information

obtained: validation controls can be included in the diﬀerent questions, time to answer the

questions is reduced and the analysis and dissemination of information is faster. Where data

are collected via diﬀerent routes (such as Internet collection in parallel with face-to-face

interviews), controls are needed to avoid duplication of information.

23Essential features and census methodology 23

4. Examples of combined methodologies

1.106. ere are many diﬀerent approaches to the implementation of combined census meth-

odologies. ese diﬀerences can be categorized according to whether a non-continuous or

continuous approach is adopted, and the ways and extent to which the diﬀerent data sources

are used. Methods used by countries using either a fully register-based census approach or

one based partly on administrative sources are examined in detail in a research report.

is

report presents information for six fully register-based and ten partly register-based countries,

giving information on the methods used to combine register and survey data, and to com

pensate for missing information. e use of repeated weighting, register estimation methods,

calibration of data, and microdata or macrodata integration are discussed.

4.1. Non-continuous approach

(a) Base register

and/or integrated administrative sources

with full ﬁeld

enumeration

1.107. One approach can be to combine the full enumeration with a base register or regis

ters.

e questionnaire used in the total enumeration then contains fewer questions com-

pared to a traditional census questionnaire, but still covers the whole population of indi-

viduals, households and dwellings. Over time, countries may decide to adopt this model,

increasing in successive censuses the use of integrated administrative registers and reducing

the number of questions in the questionnaire. e registers can be used to preﬁll such infor

mation as name, address, family composition, education, occupation and dwelling charac-

teristics on the questionnaire. ese preﬁlls can then be used to ask the respondents if the

information is still valid or needs to be changed. at can greatly reduce the work involved

in coding of the census questionnaire.

Advantages and disadvantages

1.108. e main advantages with using this model is that it will reduce the response burden

for respondents and reduce the cost of the census. e model also allows the preparation of

small-area statistics as all variables are collected as total counts. However, this model will still

involve a large data-collection exercise with the use of enumerators. Mail out/mail back data

collection may sometimes be used, but a signiﬁcant proportion of respondents may require

enumerator follow-up and assistance in completing the questionnaire.

(b) Base register and/or integrated administrative sources with ad hoc sample survey(s)

1.109. Another model involves the use of an ad hoc sample survey instead of a full enumera

tion.

e backbone register could then be used as a sample frame and also to preﬁll some

information such as name and address on the questionnaire. e ad hoc sample survey ques

tionnaire can be speciﬁcally designed to complete and statistically correct the data coming

from registers, covering those variables not available from the register. e sample can be

sized and stratiﬁed in such a way that data are available for small groups and geographic areas.

Advantages and disadvantages

1.110. is model requires far fewer enumerators than a full enumeration, so a more speciﬁc

training operation with skilled and prepared professional interviewers can be carried out. e

follow-up of the operation is also simpler. ere is no need to obtain information from each

member of the population, giving a clear reduction in response burden. Non-response can

be corrected in the sample by the use of statistical techniques to ensure information is still

representative of the population.

Eric Schulte Nordholt, Eﬃciency

in Population Censuses: The Situ-

ation of the European Register-

Based 2011 Censuses, available

from www.statistics.gov.hk/wsc

/STS067-P3-S.pdf.

Examples of base registers could

be population register and/or

dwelling register; and address

Examples of integrated adminis-

trative sources could be admin-

istrative or statistical registers of

education and/or occupation.

In Europe in the 2010 round of

censuses, four countries applied

this approach: Estonia, Latvia,

Liechtenstein and Lithuania. For

more details, see UnitedNations

Economic Commission for

Europe, Measuring Population

and Housing: Practices of UNECE

Countries in the 2010 Round of

Censuses (Geneva, 2014), p. 12,

available from www.unece.org

/ﬁleadmin/DAM/stats

/publications/2013/Measuring

_population_and_housing

_2010.pdf.

In the 2010 round of censuses,

countries that applied this

approach included Germany,

Israel, Poland, Spain, Switzerland

and Turkey. For more details,

see United Nations Economic

Commission for Europe,

Measuring Population and

Housing: Practices of UNECE

Countries in the 2010 Round of

Censuses (Geneva, 2014), p. 12,

available from www.unece

.org/ﬁleadmin/DAM/stats

/publications/2013/Measuring

_population_and_housing

_2010.pdf.

Principles and Recommendations for Population and Housing Censuses, Revision 324

1.111. By using a sample and a much smaller number of enumerators, a signiﬁcant reduc-

tion in the cost of the census is possible, in particular when compared with the traditional

approach.

1.112. e extent to which this model can produce detailed statistics (in particular for

municipalities or smaller geographic areas) will depend on the size of the sample survey.

A larger sample should allow more detailed statistics to be produced but this will correspond

ingly increase the ﬁnancial cost of the exercise. Even with a large sample, the availability of

detailed information is likely to be lower than if a comprehensive approach were taken—such

as with a traditional census or fully register-based exercise.

4.2. Continuous approach

(a) Rolling census

1.113. In a rolling census, information is collected on individuals, households and dwellings

by a continuous cumulative survey covering the whole country over a period of time (gen

erally years), rather than a particular day or short period of enumeration.

e two main

parameters of a rolling census are the length of the period of enumeration and the sampling

rate (which depends on the geographic levels required for dissemination purposes). For exam

ple, it is possible to build a sample framework in order to produce national results with one

annual survey, regional results by cumulating three annual surveys, and small-area results by

cumulating data over ﬁve years. Annual surveys may be conducted over the full course of the

year or in a particular month or other shorter time frame.

1.114. Implementation of such an approach requires highly complex sampling and model

ling techniques; a high-quality sampling frame in order to allow sampling at very low levels

of geography; and successful consultation to gain acceptance of the approach with major

stakeholders, including national and local governments and the user community.

Necessary conditions

1.115. e necessary conditions partly depend on the complexity of the sample framework.

If the sampling units are addresses, a master address ﬁle is to be built ﬁrst. But if the sampling

units are larger, for example municipalities, it is only necessary to have enough information to

spread the municipalities over the diﬀerent years. It will be necessary to explain to statistics

users the impact of the rolling sample on the use and interpretation of data, as many users

are more used to snapshot data rather than period data.

Advantages and disadvantages

1.116. e main advantage of the rolling census approach is the higher frequency for updat

ing data: a traditional census provides benchmarks every ﬁve or, more commonly, ten years.

In contrast, the rolling census provides annual updates. Another advantage is the reduction in

the burden on the public. e high peak costs and labour requirements of a traditional census

are instead spread over a longer period. Furthermore, it is possible to improve the census pro

cess over time, and to test methodological reﬁnements and new technologies as they emerge.

1.117. e disadvantage is that the rolling census approach no longer provides a snapshot of

the whole population, complicating comparisons between areas due to diﬀerent enumeration

times. In addition, as the rolling census covers the whole country over a period of time, some

respondents will move. us some people may be surveyed several times and others may not

be surveyed at all. As a result, universality might not be ensured unless careful methodologi

cal adjustments are made.

In the 2010 round of censuses

France was the only country

applying this concept.

25Essential features and census methodology 25

5. Some considerations for census taking and content

1.118. It is better to begin a rolling census just after a full traditional census, in order to

exploit the recent census information to build the sample framework. As the operation is

annual, the process must be very carefully prepared, since any delay can be problematic for

the following stages.

1.119. A rolling census is able to include all usual census topics. ere is also the possibility

of changing the questions more regularly than in a decennial cycle. is enables the census

to be more reactive to changes in the needs of users, even if comparability over time should

in principle be preserved. However, only if the questions are stable over a number of years

can a rolling census produce statistics at the same level of detail. Depending on the census

organization and procedures, it may be possible to add some thematic surveys if required.

V. Operational aspects for register-based

census or combined methodology

1.120. is section presents general operational aspects that apply to various census meth-

odological approaches making use of data from registers, including register-only-based cen-

suses, and censuses based on a combination of data from registers and other sources, such as

ad hoc sample surveys or full ﬁeld enumeration.

A. General aspects and preconditions

1.121. Population and housing censuses are an integral part of the system of oﬃcial statistics

in each country. ey are expected therefore to fully encompass the fundamental principles

of oﬃcial statistics.

(a) Legal framework

1.122. If administrative data are used for census purposes, statistical authorities should have

a clear legal mandate to collect administrative data for statistical purposes. Individual his

torical, cultural and political factors of each country lead to highly diverse legal frameworks.

— Data access. A legal basis should enable the statistical authority to collect admin

istrative data. e required data sources should be described clearly. Data sup-

ply by governmental or private organizations should be speciﬁed as compulsory.

Limitations to the data access (for example duration of access, conﬁdentiality)

should be described.

— Privacy, integrity and security. To secure the handling of data and strengthen

the trust from the general public, some legal acts should be in place. Examples of

these are a statistical act, a privacy act and a data act. ese should regulate how

data can be transferred, handled and delivered inside the statistical institute and

between the institute and other departments, organizations and users.

— Data use. All variables of census relevance, with metadata, including identiﬁers

of administrative data sources, should be listed completely and described clearly.

Limitations to the data use (for example duration of use, deletion of microdata)

should be described. Furthermore, it should be clearly deﬁned that data compiled

Principles and Recommendations for Population and Housing Censuses, Revision 326

for statistical purposes will not be retransmitted to the data-providing organiza-

tion or other governmental authorities.

(b) Cooperation

1.123. A joint eﬀort towards register-based statistics production requires ﬁrm and explicit

commitment at the highest possible political level, as well as close collaboration among rel

evant authorities. Cooperation between statistical and administrative authorities generates a

mutual and deeper understanding of the primary purpose of the registers and the needs of

the statistical authority.

1.124. In the context of a census, the most important principle for the population is the

conﬁdential use of individual information, as stated in the sixth Fundamental Principle of

Oﬃcial Statistics, which requires that the use by statistical authorities of individual data,

whether they refer to natural or legal persons, be strictly conﬁdential and used exclusively

for statistical purposes.

1.125. e political decision concerning the use of administrative data in a census can be

highly inﬂuenced by public approval or refusal. In the run-up to implementing a new or

modiﬁed census methodology it is helpful to inform the public about the project. It can be

expected that people will become increasingly sensitive towards the collection and analysis of

personal data by governmental authorities. In addition to outlining the general beneﬁts and

risks of the use of administrative data, information to the public should focus on the conﬁ

dentiality of personal microdata. Clear limits and rules regarding the use of administrative

data provide a common understanding that individual data collected for statistical purposes

will not be passed on to other governmental authorities.

(d) Administrative routines

1.126. A decision about the use of register data for statistical purposes largely depends on

the nature of the register itself, including qualities such as integrity, reliability and lifespan.

For this reason, there should be conﬁdence in the administrative authority’s capacity to be a

reliable partner and data supplier. is implies the presence of administrative routines and

safeguards. Does the administrative authority have extensive experience with the collection of

the data that may be used for statistical purposes? Is the administrative authority well organ

ized and is it anticipated that the necessary data collection will continue into the future? Are

there existing quality guidelines for the administrative authority that guarantee long-term

data quality? ese are some of the questions that need to be elaborated upon in terms of

assessing the feasibility of exploiting administrative registers for statistical purposes in general,

and for the purposes of generating census statistics in particular.

(e) Identiﬁers

1.127. Regardless of the census methodology adopted, it is extremely important that a

unique primary key variable is used in all the data sources. e use of a unique identiﬁer is

essential in order to link information successfully. is primary key may already exist in the

country—for example, a national personal identiﬁcation number. Where it does not exist,

or exists but with poor quality (for example, too many duplicates), it can be artiﬁcially cre

ated for statistical purposes. A statistical linkage key can be built from unchanging variables

for persons, such as “family name at birth”, “ﬁrst name”, “date of birth”, “sex” and “place of

birth”. Care needs to be taken with alternative spellings, for example, incorrect or incom

plete registry entries, transcription errors, and the varying transcription of foreign languages,

names or place names.

27Essential features and census methodology 27

1.128. Unique identiﬁers assist in the detection (and correction as necessary) of identical sta-

tistical units (duplicates). Duplicate records most often arise when collecting data from more

than one decentralized register, but are also possible within one centralized register. e prob

lem with duplicate data entries is the risk of multiple counting of identical statistical units.

1.129. In the case of fully register-based censuses, information from diﬀerent registers should

be matched using good-quality identiﬁers. It is important to deﬁne how often information

from diﬀerent sources is updated and the reference date of the information stored in the

diﬀerent registers. When two or more data deliveries with the same content from the same

administrative authority are planned, a linkage key will enable validation of data quality with

regard to the statistical reference period.

1.130. Successful data linkage may be compromised by poor quality of the source data.

Information stored or provided by data owners may have errors resulting in non-linkage or

multi-linkage of records. In these situations, probabilistic approaches that choose the closest

candidate, or the use of geographic information (starting from the lowest detail level and

gradually increasing), can help to improve the linkage process.

B. Collection and processing

1.131. Partially (combined) or fully register-based censuses have several important advan-

tages when compared with the traditional approach. For example, the response burden on the

population can be reduced.

Methods may be adapted to the speciﬁc national circumstances.

Non-response can be treated with methods that make use of the information that exists in

other data sources.

Depending on the amount of information available from diﬀerent data

sources and its degree of integration, data processing can be more complex with these census

methods than with a traditional census, although good-quality results can be obtained.

1.132. e decision to use administrative sources in the statistical production process requires

close collaboration between the administrative authorities and the national statistical oﬃces.

During preparations for data delivery, all parties concerned must agree on date(s) of delivery

and the content of the data. is implies a bilateral agreement at a high hierarchical level on

a detailed data set description, scheduled delivery dates and the statistical reference period.

Test data deliveries help to solve or minimize problems with the subsequent data processing

by the national statistical authority. Validation techniques appropriate to administrative data

should be applied, including checks on the plausibility, completeness and reference periods.

1.133. For combined census methodologies, it is important to store control information and

indicators at the lowest geographic level available in the central database, covering issues

related to the census operation, such as progress with the ﬁeldwork, response rates and com

parisons with information in registers. is control information—normally based on web

reports and analysed daily by project managers or regional oﬃces—can be used to detect

problems that appear during the ﬁeldwork and to plan necessary actions to overcome these

problems. If data are analysed on a daily basis, close monitoring of the continuing ﬁeld opera

tion and data entry is possible.

1.134. Register information may contain errors (for example, records showing people as

being implausibly old, invalid occupations, information about migration that is not con

sistent with other data). Edit rules may be deﬁned to highlight inconsistent or implausible

information. Correction or imputation of records with errors can be attempted in diﬀerent

ways: ﬁrst, if possible, using another data source (register) that also has information about that

speciﬁc record and topic; or second, carrying out probabilistic imputation based on available

information that is thought to be reliable.

Statistical variables can be

derived using one or more

administrative variables from

diﬀerent data sources.

For example, information that

exists in other registers or in dif-

ferent surveys.

Principles and Recommendations for Population and Housing Censuses, Revision 328

1.135. Missing or implausible data can create serious problems for data analysis. Cases that

have missing or implausible values may be deleted, but this can result in a loss of representa

tiveness and completeness, and the introduction of bias. Various imputation methods can be

considered, with a general distinction between single and multiple imputation techniques.

1.136. Sometimes information about topics can be obtained through diﬀerent data sources

(registers and survey). In this situation, it is very common that calibration techniques are used

in order to reduce inconsistencies between data from diﬀerent sources. However, calibration

only guarantees coherence to a certain geographic level, generally modifying or adjusting

the sampling factors. It may be necessary to explain to users the reasons for any remaining

diﬀerences.

VI. Use of sampling in population

and housing censuses

1.137. e potential role of sampling in population and housing censuses is extensive. On

the one hand, sampling can be an integral part of the planning, data collection and opera

tions, analysis and evaluation of the census.

On the other hand, the census may serve as a

sampling frame for subsequent sample surveys or survey programmes.

1.138. e elaboration of the features of acceptable sampling operations presented below

refers primarily to the traditional census; however, it also applies to any of the combined

methods wherein sample surveys represent a critical component of the method.

A. Features of acceptable sampling operations

1. Accuracy and precision

1.139. e use of sampling in a census entails an awareness of the precision desired in sample

estimates. e higher the levels of precision or the smaller the domain of estimation, the larger

and more complex, and hence the more expensive, the sample. A distinction is to be made

between the precision of a sample estimate and its accuracy. Precision can be measured by the

standard error (which gives a measure of the error due to sampling compared with a complete

enumeration under the same general conditions of enquiry), while accuracy is measured by

the diﬀerence between the true value (which is generally unknown) and that obtained from

an enquiry, whether on a sample or complete enumeration basis.

1.140. Sampling methods employed in census-taking, with the exception of pilot tests,

should make use of probability samples as opposed to judgemental, purposive or other non-

scientiﬁc methods. For the successful execution of a probability-based sampling plan, it is

essential that scientiﬁcally designed selection procedures be strictly followed. e sampling

procedures must be such that a known positive probability of selection can be assigned to

every unit in the population. e inverse of these probabilities must be calculable so that they

can be used to estimate population values and to calculate the measure of precision of the

estimates (in other words, their sampling error). Selection procedures must be faithful to the

design so that deviations from prescribed standards or instructions are minimal.

1.141. Of course, estimated results based on samples are subject to sampling errors in addi

tion to various types of non-sampling errors that are also present in a complete enumera-

tion. e smaller scale of a sample operation may make it possible, nevertheless, to employ

Reference is made to paragraphs

3.9-3.17 and 3.220-3.227

of this publication and to

UnitedNations Statistics

Division, Post Enumeration

Surveys: Operational Guidelines,

Technical Report (2010), available

from https://unstats.un.org

/unsd/demographic/standmeth

/handbooks/Manual_PESen.pdf.

29Essential features and census methodology 29

interviewers with advanced training, to devise and pose questions of greater detail and to

minimize response errors. As a result, non-sampling errors, which aﬀect the accuracy of the

estimates, are likely to be fewer in a well-executed sample than in a complete enumeration.

1.142. Whenever sampling is used in the census data collection, provision should be made

for computing estimates of sampling error (variances), at least for the major items of interest.

While a variety of techniques can be employed to estimate variances, the particular technique

adopted should be one that reﬂects the actual sample design used.

B. Census resources

1.143. Eﬀective planning of sample operations consists to a large extent in making judicious

use of whatever expert knowledge and equipment are available in a particular country. Spe

ciﬁc sample plans aimed at the same objective may vary from country to country, depending

on the quality and quantity of census resources. In planning a sample operation as part of the

census eﬀort, it is important to bear in mind considerations of cost and competent direction.

1.144. e question of cost in sampling is of crucial signiﬁcance, and cost may be the reason

why it was decided not to collect the same information through a complete enumeration in

the ﬁrst place. Numerous factors govern the cost of sampling, and it is essential that these

be fully weighed before a decision is made to associate a sample plan with a complete count.

One important factor, for instance, is the size and complexity of the sample, which in turn is

governed by the objectives of the survey and the procedures that are regarded as most eﬃcient.

1.145. Sample operations should be conducted under the direction of a competent statistician

who is conversant with the theory of sampling and of statistical analysis from sample data,

and the practical operations of carrying out sample surveys in the ﬁeld. e advice of such

a sampling statistician is indispensable at all stages of the sample operations, from planning

and sample design to estimation and calculation of variance.

1.146. In order to ensure that the sample is selected strictly according to the design and to

avoid any possibility of bias in sample selection, it is strongly recommended that the actual

selection of the sample units should be carried out either in the central oﬃce or in regional

oﬃces under the direct supervision of a sampling statistician.

Part two

Planning, organizing and management

I. Introduction

2.1. is and the subsequent part of the Principles And Recommendations focus on tradi-

tional population and housing censuses. Part two elaborates on planning, organization and

management of the population and housing census, as this is a peculiar and most complex

statistical exercise requiring a multidimensional and simultaneous approach to preparation

and management, while part three follows the Generic Statistical Business Process Model

in presenting census operation activities.

II. Overall census planning

2.2. A population and housing census (or a population census by itself) consists of a

complex series of interrelated steps, and constitutes perhaps the single most extensive, com

plicated and expensive operation that a country undertakes. Some of these steps, for example

the printing of the census questionnaires, may be massive in scale; other steps, for example

the training of the supervisory staﬀ, must be carried out in a uniform manner in all parts

of the country; and still others, for example the actual enumeration, must incorporate both

features. Also, since censuses take place after ﬁve to ten years, the planning and prepara

tion for each new census round has to take into account changes in ﬁeld conditions, census

methodology, technological innovations, user requirements, census questions, personnel and

societal conditions.

2.3. To ensure that the diverse operations occur in their proper sequence and in a timely

manner, the entire census and its various component steps must be planned carefully in

advance. An apparently minor oversight in planning may lead to serious defects in the census

results and to costly ineﬃciencies in the census operations. Careful planning is therefore criti

cally important to a successful census, not only in countries with comparatively little statistical

experience but also in those with a well-developed system of statistics. Coupled with the need

for careful planning is the need for appropriate organizational and administrative arrange

ments and procedures. Such arrangements and procedures are necessary to ensure both that

the extensive human and material resources mobilized for the census are eﬀectively and eﬃ

ciently used, and that its very tight time schedules and massive logistic requirements are met.

2.4. It must be stressed, however, that at each stage of census planning and implementation,

the various administrative arrangements developed will need to be guided by sound technical

considerations. e quality and timeliness of the census data will almost certainly suﬀer unless

suﬃcient and appropriate weight is given throughout the census to a wide range of subject

matter and statistical requirements. is is especially valid in the case of cross-cutting issues,

such as information technology, present throughout many essential phases of the census. It is

United Nations Commission for

Europe, on behalf of the Inter-

national Statistical Community,

Generic Statistical Business Process

Model (GSBPM), Version 5 (2013).

Principles and Recommendations for Population and Housing Censuses, Revision 332

for this reason that the management of a large statistical operation, and especially a population

and housing census, cannot be considered a routine administrative assignment.

2.5. Not all censuses follow a uniform pattern but there are certain major elements that

must be taken into account in every one of them. In general, census operations can be divided

into seven phases: (a) preparatory work and testing, (b) enumeration, (c) data processing,

(d) building of databases, (e) evaluation of the results, (f ) dissemination of the results, and

(g) analysis of the results. In addition, distinct sets of operations related to the systematic

recording of census experience and the quality assurance and improvement programme must

accompany and support the main census operations. It will be readily apparent that these

phases are not entirely separate chronologically or mutually exclusive. For example, some cen

sus results are usually released before all data-processing activities are completed; the analysis

and the dissemination of census results overlap quite extensively; and the systematic record

ing of census experience should start at the beginning of the preparatory work and continue

through all subsequent phases. Furthermore, certain elements that are discussed below, such

as the budget and staﬀ, may have to be amended according to the circumstances arising at a

later stage of operations. e elements of each of these phases are discussed below in terms of

their implications for sound census management.

2.6. When the housing and population censuses are carried out together, the planning,

organization and administration of the two censuses should be considered separate aspects of

a single, integrated ﬁeld and processing operation; that is, the separate technical requirements

of each census have to be taken into account in planning and carrying out the combined

operation. A combined population and housing census will be more costly and complex than

each census considered by itself but less expensive than the total operation of carrying out

both censuses independently. Moreover, the combined census will be capable of providing a

greater wealth of cross-tabulations than both censuses carried out independently. Each coun

try will have to decide on the trade-oﬀs involved in light of its own needs and circumstances

(see also paragraphs 1.38-1.41). However, from the perspective of overall census planning and

management, the decision is not a critical one. Whether the census is a combined operation

or a separate population or housing census, the basics of census planning, organization and

administration as described below remain unchanged, except for the added cost and complex

ity of the combined operation.

III. Strategic objectives and management

A. Strategic objectives

2 .7. e development of plans for a census should include the early preparation of a set

of strategic aims and objectives that may be used to guide the implementation of the plans,

set standards and form a set of benchmarks against which outcomes can be assessed to help

determine the success of the census. Ideally, the starting point for developing these objectives

would lie in combining information derived from evaluating previous census experience,

from understanding user requirements for information from the census and from assessing

changes in both society and technology. In practice, some of this information is diﬃcult to

obtain and often provides conﬂicting guidance. Nevertheless, such objectives can be used

to assist in planning major elements of the process. Although the strategic objectives of the

census will be speciﬁc to individual countries and will diﬀer according to local circumstances,

they can be described under the following headings: census content, impact on the public and

on census staﬀ, production of census results, cost-eﬀectiveness and cost-beneﬁt.

For a discussion of statistical

management generally, see

Handbook of Statistical Organiza-

tion, Third Edition: The Operation

and Organization of a Statistical

Agency, Studies in Methods,

No.88 (United Nations publica-

tion, Sales No. E.03.XVII. 7).

33Planning, organizing and management 33

2.8. Census content. e aim is to ensure that the topics are appropriate for meeting the

demonstrated requirements of users, taking into account considerations of cost-eﬀectiveness,

human resources, time availability and respondent burden. Subsidiary objectives under this

element relate to (a) suitable consultation with existing and potential users at all stages;

(b) establishment of measurable standards of reliability incorporating user views on priori

ties; and (c) adequate testing of new topics to ensure successful collection and production of

reliable results.

2.9. Impact on the public and on census staﬀ. e aim is to ensure that all the aspects

of collection operations and the dissemination of results are acceptable to the public and

fully comply with legal and ethical standards for protecting the conﬁdentiality of individual

responses. e public should be fully informed about census objectives, content and methods,

as well as about their rights and obligations with respect to the census. Similarly, all census

staﬀ must be fully aware of their responsibilities. Subsidiary objectives include such issues as

(a) keeping completed forms and other records containing personal information secure and

conﬁdential; (b) ensuring that public support for all aspects of the census is as strong as pos

sible; and (c) producing requested customized output in a manner consistent with preventing

disclosure of personal information, adhering to established reliability standards for the release

of data, and implementing policies designed to safeguard the access of all users to census results.

2.10. Production of census results. e aim is to deliver census products and services, and

to meet legal obligations and user needs with stated quality standards and a predetermined

timetable. Subsidiary objectives include (a) producing outputs with a minimum of error suit

able for the purposes for which the data are to be used; (b) providing standard outputs for

the main results and services for customized output; (c) providing access to output; (d) using

geographic bases appropriate for collecting and referencing data for output; (e) improving

methods of enumeration, particularly in diﬃcult areas, so as to reduce levels of undercoverage

and response error; (f ) improving methods of evaluation and the means to convey ﬁndings

to users; and (g) developing a measure of quality and targets.

2.11. Cost-eﬀectiveness. e aim is to plan and carry out a census as inexpensively as pos

sible without compromising other strategic objectives. Subsidiary objectives relate to mini-

mizing costs by (a) adopting more eﬃcient data collection, data capture and data-processing

approaches and related technologies; (b) contracting out appropriate parts of the operation;

for cost recovery and income generation; (d) international collaboration and reuse of systems;

(e) encouraging the public to self-complete forms online or on paper where possible; and

(f ) replacing direct collection of data with use of administrative data.

2.12. Cost-beneﬁt. e aim is to increase the value or beneﬁt generated from the census

while also managing the overall cost. Increasingly, large programmes such as the census are

expected to demonstrate and quantify the beneﬁts that the census programme will deliver.

In eﬀect, the value of the census should be greater than, or at least equal to, the cost of con

ducting the census. No programme can be considered a success unless the beneﬁts of that

programme are realized. e beneﬁts from census products and services are those that are

realized through the uses of the census, some of which are outlined in paragraphs 1.19 to 1.37.

Some of the beneﬁts generated through the use of the data can be quantiﬁed, while other

beneﬁts of the data are more diﬃcult to measure, but are nonetheless important and should

be noted in any cost-beneﬁt analysis for conducting a census. Some of these beneﬁts depend

on statistical agencies being open with information to encourage and inform debate about

the eﬀectiveness of government and government policies. erefore, key to the planning of

the census is to ensure that there is some identiﬁcation of the beneﬁts (whether estimated in

ﬁnancial terms or not) and that the plans focus on realizing these beneﬁts.

Principles and Recommendations for Population and Housing Censuses, Revision 334

2.13. In the context of costs, it is of paramount importance to aim at emphasizing the

beneﬁts of the population and housing census in terms of the information it generates. In

essence, a cost-beneﬁt analysis needs to be incorporated as one of the major components of

the census so as to outline the costs of not having the necessary information and its conse

quences. While the beneﬁts of the census and statistics it generates transcend local, regional

and national needs and can and should be clearly quantiﬁed, there are also intangible beneﬁts

such as national pride in conducting such an exercise. Subsidiary objectives include illustrat

ing the value of the census as an educational tool and framework, for comparative purposes

at national and international level and as a cornerstone of the national statistical system.

2.14. ese objectives can be used as benchmarks to assess user requirements and may also be

built into appraisal systems that, with suitable weighting, can be used to compare and review

options. In general, strategic objectives of the population and housing census need to be clearly

emphasized throughout the process of preparing, conducting and exploiting census data.

B. Strategic management

2.15. e primary value of strategic management is to assist census organizations to operate

successfully in a dynamic, complex environment. e strategy drives key strategic decisions

and choices over the term of the census undertaking in response to external and internal

forces. e crafting of a strategy for a project or programme such as a census is critical for

successful execution, and is dependent on a variety of knowledge and skills in diﬀerent areas.

While the crafting of the strategy is an art, it is important that it is governed by a systematic

process to ensure careful examination and consideration of all issues that might have an inﬂu

ence on the future state of the programme. Census organizations may consider adopting the

following strategic management process that will guide census operations in all its phases.

2.16. e strategic management process consists of four phases, namely:

(a) Strategy analysis;

(b) Strategy formulation;

(d) Strategy monitoring and review.

2 .17. Strategy analysis is about ascertaining the issues that need to be addressed to take

corrective action or to chart a new direction. It seeks to change the organizational set-up to

one that is systemic, holistic, comprehensive and coordinated. Strategy analysis consists of:

(a) Setting the direction for the census operation, with the objective of reaﬃrming

its purpose and the way it should conduct its business;

(b) Setting strategic goals for the census operation by way of deﬁning what the system

aims to achieve in terms of deﬁning its highest goals and strategic outcomes. Strate

gic outcomes and goals must be aligned to what the user can expect and must there-

fore address user needs and requirements. A strategy driven by outcomes means

“planning backwards” from the desired outcome through how best to achieve it;

status or situation and identifying the key issues that need to be addressed. Ana

lysing the internal and external environment provides the evidence base to inform

the development of the strategy. is analysis of the situation forms the basis of

the strategy and its objectives to be deﬁned. Census organizations may consider

using a SWOT (strengths, weaknesses, opportunities, threats) analysis to do a

strategic analysis of the internal and external environment.

35Planning, organizing and management 35

2.18. Strategy formulation is about deﬁning how and where the census organization must

respond. e key steps involved in this phase include (a) develop and review the value chain;

(b) develop strategic objectives and subobjectives; (c) compile a strategy map; (d) deﬁne the

strategic intent; (e) identify critical success factors; (f ) identify strategic risks; and (g) identify

or develop strategic interventions.

2.19. Strategic objectives drive a strategy. ey provide direction on what should be done

to achieve the strategic goals and outcomes. All activities in the census should be linked to a

strategic objective, whether it is a new activity, an improvement initiative or maintaining the

current status. Strategic objectives provide speciﬁc direction to the activities of the census opera

tion and form the foundation upon which decisions are made. ey also provide the direction

for everyone in the organization and motivate people to achieve them, especially if they are

rewarded. Strategic objectives aﬀect other aspects of management, such as planning, organizing

and leading, and provide a benchmark for performance measurement as well as a mechanism

of control through provision of corrective measures. Finally, strategic objectives form the basis

for delegation of authority. Good objectives are helpful in eﬀective delegation of authority.

2.20. e strategic objectives, as formulated, must be speciﬁc, measurable, achievable, rel

evant and time-bound (SMART).

2.21. Strategy implementation is the process that turns strategies and plans into actions in

order to accomplish strategic goals, outcomes and objectives. Implementing the strategic

plan is as important as, or even more important than, developing the strategy. e key steps

involved in this phase include:

(a) Compiling a census strategic plan, work programme and operational plan with

the following elements:

i. Work planning: Compiling the operational plan by deﬁning the inputs, pro

cesses and outputs;

ii. Resource planning: Identifying what human and other resources are required

and how these resources should be deployed and developed to create the

competences need to deliver the strategy;

iii. Financial planning: Compiling the budget outlining the funding required

to implement the strategy;

iv. Risk planning: Identifying the operational risks and developing control and

mitigating actions in response to those risks;

(b) Translating the strategy into action through:

i. Deﬁning the body of work (identifying key performance indicators, outputs

to be delivered, targets and milestones that will deliver the strategy);

ii. Deﬁning the method of work (developing a value chain at conceptual and

operational levels, including the quality management process that deﬁnes

how customer value will be delivered);

iii. Deﬁning the organization of work (designing an organizational structure

that implement the strategy),

2.22. Strategy monitoring and review is about monitoring and reporting on the progress,

achievements and challenges in the programme; taking corrective action where required; and

evaluating the impact of the changes and improvements. Implementation must be monitored

to be successful. Due to constantly changing external and internal conditions, census manag

ers must continuously review both environments as new strengths, weaknesses, opportunities

Principles and Recommendations for Population and Housing Censuses, Revision 336

and threats may arise. e key element in strategy monitoring is to get the relevant and timely

information to take corrective actions where required.

C. Avoiding gender biases and biases aﬀecting

indigenous peoples and minorities

2.23. Gender-based stereotypes can introduce serious biases in census data and the conclu-

sions drawn from these data. ese biases are discussed in more detail in part four (see for

example paragraphs 4.129-4.135 and 4.289-4.351 relating to household relationships and

economic characteristics, respectively). ere is much that can be done in the preparatory

stages of the census to help minimize gender-based biases. ese preparatory activities are

of two broad types: those related to census content and those related to census operations.

2.24. Issues of census content, including what information is sought and how, the deﬁ

nitions and classiﬁcations used, and the manner in which databases and tabulations are

speciﬁed, are important in generating data needed to examine questions of gender equity. In

addressing these content issues, census planners and users will need to be alert to prevailing

stereotypes so as to develop a census that both minimizes the inﬂuence of the stereotypes that

respondents and enumerators may hold and avoids further perpetuation of these stereotypes.

2.25. With regard to census operations, particular attention will need to be given to the

selection, training and supervision of the ﬁeld staﬀ. is involves ensuring that both men and

women are recruited to the ﬁeld staﬀ (both as interviewers and supervisors) and that manu

als and training materials cover gender bias issues just as they do other important sources of

error. Consultations with women’s groups and others concerned with gender equity can help

in addressing both content and operational issues.

2.26. Gender-related stereotypes and biases are concerns that have relevance for all coun

tries. Census authorities in a number of countries must also be alert to the possibility of

stereo types and biases aﬀecting data on minority population groups. Such groups may include

ethnic, linguistic, national, racial, religious, indigenous and nomadic populations. Persons

with disabilities may often be subject to similar bias. As with gender issues, the problem will

need to be addressed in terms of both census content and census operations. Representatives

of these minority groups can often provide census planners with important information

and insights relevant to both census content and operations (for detailed information about

diﬃcult-to-enumerate groups, see paragraphs 3.125-3.134 and 4.48). us, special eﬀorts

should be made to consult with them when planning the census. In the case of indigenous

and minority populations living in isolated settlements or enclaves, such consultations are

often critical for minimizing underenumeration among these populations.

IV. Units, place and time of enumeration

A. Units of enumeration

2 . 27. Since individual enumeration is an essential feature of a population and housing cen-

sus, clarity about the unit of enumeration is an essential element of census planning. In the

case of the population census, the primary unit of enumeration is the person. ere are two

general frameworks within which individuals are identiﬁed: (a) households, and (b) institu

tions, as a subset of collective living quarters. e household is a general framework within

which most individuals are identiﬁed, since the majority of the population live in households,

37Planning, organizing and management 37

and the household is also a unit of enumeration in its own right. Because the household is

also a unit of enumeration for the housing census, careful identiﬁcation as a preliminary

step in the enumeration can facilitate the eﬃcient collection of the data and the control of its

completeness in both types of census.

2.28. As mentioned in the previous paragraph, the second framework within which indi

viduals are identiﬁed comprises “institutions”, as a subset of collective living quarters. In

addition to persons identiﬁed within households, there are persons living in institutions who

are not members of a household. is group constitutes the “institutional population”, which

is also investigated in population censuses.

2.29. For the housing census, the household is one of the three units of enumeration; the

other two units are living quarters (in other words, housing units and collective living quar

ters) and buildings. It is important to bear in mind that, in conceptual terms, these three

units are clearly distinguishable. ere is not necessarily an identity or exact correspondence

among these concepts nor are the terms themselves interchangeable. Several households may

live together in one set of living quarters and one household may occupy more than one set

of living quarters. Similarly, several sets of living quarters may together occupy one building

and one set of living quarters may occupy more than one building.

2.30. It is recognized that there may be diﬃculty in some countries in maintaining inde

pendent concepts of “household” and of “housing unit”.

However, the advantages in terms

of the usefulness of the data that result from preserving separate concepts usually outweigh

the additional eﬀort required in maintaining them.

2.31. In carrying out a census, it is essential that the units of enumeration be clearly deﬁned

and that the deﬁnitions be included in manuals of instruction for the enumeration and,

to provide appropriate guidance for users of the resulting statistical information, in census

reports. In order to reduce the possibility of diﬃculties in applying the deﬁnitions recom

mended below, countries may ﬁnd it necessary to expand the deﬁnitions and to illustrate

them in terms of national conditions and circumstances. Post-enumeration ﬁeld checks can

provide a useful means of determining to what extent the national deﬁnitions of the units

of enumeration have been applied in the ﬁeld and the consequent eﬀects on census results.

1. Person

2.32. For census purposes, the term “person” denotes each individual falling within the

scope of the census. As emphasized above (paragraph 2.27), a person can be identiﬁed as

belonging to the household population (that is to say, the population living in households)

or to the institutional population (that is to say, the population living in institutions, as a

subset of collective living quarters), as deﬁned in paragraph 2.39 below. Although each person

must be included in the count of the population, there will be some variation in regard to the

persons for whom information is collected on diﬀerent topics. e variations usually depend

on the person’s age (for example, questions relating to economic activity, in which case the

age boundary may be driven by national legislation), sex (for example, questions relating to

children born), or relationship to the head or other reference member of the household. It may

be recommended that information on a particular topic should be investigated for less than

the total population, and the group of persons for which a given topic should be investigated is

indicated below under the deﬁnitions and speciﬁcations of such topics presented in part four,

chapter I, section IV. In addition, the recommended tabulations for population censuses on

the website of the United Nations Statistics Division are accompanied by a description of the

population to be included in each tabulation. Similarly, the scope of the census should clearly

indicate the persons to be covered and those to be left out.

For further discussion on the

concept of households, see

paragraphs 2.33-2.37; also, for

the deﬁnition of housing unit, see

paragraph 4.427.

Principles and Recommendations for Population and Housing Censuses, Revision 338

2. Household

2.33. e concept of household is based on the arrangements made by persons, individually

or in groups, for providing themselves with food and other essentials for living. A household

may be either (a) a one-person household, that is to say, a person who makes provision for his

or her own food and other essentials for living without combining with any other person to

form a multiperson household; or (b) a multiperson household, that is to say, a group of two

or more persons living together who make common provision for food and other essentials for

living. e persons in the group may pool their resources and may have a common budget;

and they may be related or unrelated persons, or constitute a combination of persons both

related and unrelated.

2.34. e concept of household provided in paragraph 2.33 is known as the “housekeeping

concept”. It does not assume that the number of households and housing units are or should

be equal. A housing unit, as deﬁned in paragraph 4.427, is a separate and independent place

of abode that is intended for habitation by one household, but that may be occupied by more

than one household or by a part of a household (for example, two nuclear households that

share one housing unit for economic reasons or one household in a polygamous society rou

tinely occupying two or more housing units).

2.35. Some countries use a concept diﬀerent from the housekeeping concept described in

the previous paragraph, namely, the “household dwelling” concept, which regards all persons

living in a housing unit as belonging to the same household. According to this concept, there

is one household per occupied housing unit. erefore, the number of occupied housing units

and the number of households occupying them are equal and the locations of the housing

units and households are identical. However, this concept can obscure information on living

arrangements, such as doubling up, that is relevant for evaluating housing needs.

2.36. Households usually occupy the whole or a part of, or more than, one housing unit,

but they may also be found in camps, boarding houses or hotels or as administrative person

nel in institutions, or they may be homeless. Households consisting of extended families

that make common provision for food, or of potentially separate households with a common

head resulting from polygamous unions, or households with vacation or other second homes,

may occupy more than one housing unit. For more discussion of household occupancy, see

paragraphs 4.471-4.475.

2 .37. A household may also consist of one or more homeless people. e deﬁnition of the

homeless can vary from country to country because homelessness is essentially a cultural

deﬁnition based on concepts such as “adequate housing”, “minimum community housing

standard” or “security of tenure”,

which can be perceived in diﬀerent ways by diﬀerent

communities. e following two categories or degrees of homelessness are recommended:

(a) Primary homelessness (or rooﬂessness): is category includes persons living in

streets or without a shelter that would fall within the scope of living quarters;

(b) Secondary homelessness: is category may include the following groups:

i. Persons with no place of usual residence who move frequently between vari

ous types of accommodation (including dwellings, shelters or other living

quarters);

ii. Persons usually resident in long-term (also called “transitional”) shelters or

similar arrangements for the homeless.

ese deﬁnitions should be supported by a data collection strategy that ensures, for

example, that dwellings are properly identiﬁed as shelters and not households.

For the deﬁnition of tenure, see

paragraphs 4.556-4.559.

39Planning, organizing and management 39

2.38. For some topics investigated in housing censuses, the household may serve more eﬃ-

ciently than living quarters as the unit of enumeration. For example, tenure, if investigated

in the census, should be collected with reference to households rather than living quarters.

Information about household possessions that are normally included as part of the equipment

of living quarters (radio and television receivers, for example) should be collected with refer

ence to households. Information on rent, an item of signiﬁcance in relation to both living

quarters and households, would of necessity be collected in relation to the household.

3. Population in collective living quarters

2.39. As emphasized in paragraph 2.27, institutions represent the second general framework

within which persons, as major units of enumeration, are identiﬁed. e institutional popula

tion comprises persons who are not members of households. ese include persons living in

military installations, correctional and penal institutions, dormitories of schools and universi

ties, religious institutions, hospitals and so forth.

Personnel responsible for the running of

an institution and not living in dormitories or similar accommodations should be excluded

from the institutional population.

2.40. Persons living in hotels or boarding houses are not part of the institutional popula

tion and should be distinguished as members of one-person or multiperson households, on

the basis of the arrangements that they make for providing themselves with the essentials

for living.

4. Building

2.41. e building is regarded as an indirect but important unit of enumeration for housing

censuses since the information concerning the building (building type, material of construc

tion and certain other characteristics) is required for proper description of the living quarters

located within the building and for the formulation of housing programmes. In a housing

census, the questions on building characteristics are normally framed in terms of the building

in which the living quarters enumerated are located, and the information is recorded for each

of the housing units or other living quarters located within it.

2.42. A building is any independent free-standing structure comprising one or more rooms

or other spaces, covered by a roof and usually enclosed within external walls or dividing walls

that extend from the foundations to the roof. However, in tropical areas, a building may con

sist of a roof with supports only, that is to say, one without constructed walls; in some cases,

a rooﬂess structure consisting of a space enclosed by walls may be considered a building.

2.43. In some countries, it may be appropriate to use the compound as a unit of enumeration,

either in addition to the building or as a substitute for it. In some areas of the world, living

quarters are traditionally located within compounds and the grouping of living quarters in

this way may have certain economic and social implications that it would be useful to study.

In such cases it may be appropriate, during the census, to identify compounds and to record

information suitable for linking them to the living quarters located within them.

5. Living quarters

2.44. e principal units of enumeration in a census of housing are living quarters. Only

by precise recognition of these identities can data be obtained that will provide a meaning

ful description of the housing situation and a suitable basis for the formulation of housing

programmes and policies.

For more detailed deﬁnition and

speciﬁcations of institutions as a

subset of collective living quar-

ters, see paragraphs 4.453-4.455.

For the deﬁnition of rooms, see

paragraph 4.482.

The term dividing walls refers to

the walls of adjoining buildings

(for example, of row houses) that

have been constructed so as to

be contiguous.

For a more detailed discussion

of the deﬁnition of building and

related concepts, see paragraphs

4.526-4.529.

Principles and Recommendations for Population and Housing Censuses, Revision 340

2.45. Living quarters are structurally separate and independent places of abode. ey may

(a) have been constructed, built, converted or arranged for human habitation, provided that

they are not at the time of the census used wholly for other purposes and that, in the case of

improvised housing units and collective living quarters, they are occupied; or (b) although

not intended for habitation, actually be in use for such a purpose at the time of the census.

B. Place of enumeration

1. Concepts relating to the place of enumeration

2.46. In the context of the population census, a country may wish to enumerate all persons

present in the territory and/or supposedly belonging to the population of interest. Population

to be enumerated is the group of persons who the country decides should be covered by the

census regardless of their later inclusion in a population count.

2 .47. e place of enumeration would be either the place where the person is found or the

place of usual residence of the person at the census reference moment. It should be ensured

that each person should have only one place of enumeration. Countries should document the

deﬁnition of place of enumeration that they have adopted for their census and also provide

explicit instructions on how this deﬁnition should be applied at the time of enumeration to

enumerators for use during an interview or to respondents when ﬁlling in self-administered

questionnaires.

2.48. In general, usual residence is deﬁned for census purposes as the place at which the

person lives at the time of the census, and has been there for some time or intends to stay

there for some time.

2.49. Most individuals enumerated have not moved for some time and thus deﬁning their

place of usual residence is unambiguous. For others, the application of the deﬁnition can lead

to many interpretations, particularly if the person has moved often.

2.50. It is recommended that countries apply a threshold of 12 months when considering

place of usual residence according to one of the following two criteria:

(a) e place at which the person has lived continuously for most of the last 12 months

(that is, for at least six months and one day), not including temporary absences for

holidays or work assignments, or intends to live for at least six months;

(b) e place at which the person has lived continuously for at least the last 12

months, not including temporary absences for holidays or work assignments, or

intends to live for at least 12 months.

2.51. Persons who move frequently and do not have a place of usual residence should be

enumerated at the place where they are found at the time of the census.

2.52. Regardless of the criteria used to deﬁne the 12-month period, countries should ensure

that each person should have one and only one place of usual residence.

2.53. ere are various population groups for which some uncertainty may arise about

their inclusion in the usual resident population. e following persons would generally be

considered in the usually resident population:

(a) Persons found at the moment of enumeration that cannot identify their place of

usual residence, such as those who move often;

(b) National military, naval and diplomatic personnel and their families, located

outside the country;

For a more detailed discussion of

the deﬁnition of living quarters

and of the concepts of separate-

ness and independence as used

in the deﬁnition, see paragraphs

4.428-4.429.

This approach is consistent with

the Conference of European

Statisticians Recommendations

for the 2020 round of censuses.

It is also consistent with what is

recommended in the Recom-

mendations on Statistics of Inter-

national Migration, Revision1,

Statistical Papers No. 58, Rev.1,

(UnitedNations publication,

Sales No. E.98.XVII.14).

41Planning, organizing and management 41

diplomats or military forces), provided that they meet the criteria for usual resi

dence in the country;

(d) Merchant seafarers and ﬁshers usually resident in the country but at sea at the

time of the census (including those who have no place of residence other than

their quarters aboard ship);

(e) Persons who may be illegal, irregular or undocumented migrants, as well as asy

lum seekers and persons who have applied for or been granted refugee status or

similar types of international protections, provided that they meet the criteria for

usual residence in the country;

(f ) Persons who cross a frontier daily or weekly to work or study in another country,

provided that they meet the criteria for usual residence in the country;

(g) Children born in the 12 months before the census reference time and whose

families are usually resident in the country at the census reference time;

(h) Persons of minor age studying abroad for one year or more to attain the primary

or secondary level of education, regardless of the frequency of return to the family

home located within the country. If the person is also working abroad, the same

rules for cross-border workers apply;

(i) Persons who regularly live in more than one country during a year, if they are

present in the country at the moment of the enumeration.

On the other hand, the following group of persons need to be considered for being

excluded from the usual resident population:

(a) Foreign military, naval and diplomatic personnel and their families, located in

the country, regardless of their place of usual residence;

(b) Persons of minor age attending the primary or secondary level of education whose

family home is located abroad, regardless of the duration of their stay. However, if

these persons are also working in the country, then the identiﬁcation of the place

of usual residence follows the same rules as for cross-border workers;

(d) Persons who regularly live in more than one country during a year, if they are not

present in the country at the moment of the enumeration.

2.54. e concept of usual residence may be referred to as though it is synonymous with

the concept of de jure residence. In certain circumstances, however, the term “de jure” may

carry with it a requirement that the person’s residence at that place has a basis in the legal

system applicable to that speciﬁc place. In turn this implies that people without such a legal

basis should not be enumerated in that area. It is not recommended that censuses of popula

tion and housing enumerate only those people with a legal right to be in a place but rather,

as described in section 2 below, should include either all those present at the place on census

night or all those whose usual residence on census night was at the place of enumeration.

2. Operational issues relating to the place of residence

and the place of enumeration

2.55. In a population census, information about each person can be collected and entered

in the census questionnaire either where he or she is (or was) present on the day of the census

or at his or her usual residence.

Principles and Recommendations for Population and Housing Censuses, Revision 342

2.56. In compiling the census results by geographic areas, however, each person who is

part of a household can be included in either (a) the household (and hence the geographic

area) where the person was present on the day of the census; or (b) the household (and the

geographic area) where he or she usually resides. e same should apply for the institutional

population. is allocation is not necessarily dependent upon the place at which informa

tion was collected for the individual, but it can be simpliﬁed by the proper choice of a place

of enumeration.

2 .57. If a “present-in-area” population distribution is wanted, it is logical to enumerate each

person at the place where he or she is (or was) present at the time of the census. If a distribu

tion by usual residence only is required, it is more satisfactory to collect the information about

each person at the person’s place of usual residence. It should be noted, however, that it is

not always possible to collect information about each individual at his or her usual residence,

as, for example, when an entire household is away from its usual residence at the time of the

census. Some provision must therefore be made for collecting information about such persons

at the place where they are found at the time of the census.

2.58. With the growing need for information on households and families and on internal

migration, it is becoming increasingly desirable to prepare tabulations on the basis of usual

residence rather than on place-where-present, since the latter is often temporary and so is

not useful for the investigation of the above-mentioned topics. It is comparatively simple to

enumerate each person where-present on the day of the census and thus to obtain a present-

in-area population distribution of the population. However, a usual residence distribution

of the population is likely to be more useful for presentation and analysis of the resulting

information than that of the present-in-area population during the enumeration.

2.59. If the objective is to obtain information on both the usually resident population and

the present-in-area population, then either each person present in each household or institu

tion on the census day or each person present and each usual resident temporarily absent can

be enumerated at the appropriate household or institution. A clear distinction must then be

made in the questionnaire, as applicable, between (a) persons usually resident and present on

the day of the census; (b) persons usually resident but temporarily absent on the day of the

census; and (c) persons not usually resident but temporarily present on the day of the census.

2.60. Depending on the categories of persons enumerated at any given place, information

may then be collected on the usual residence (address) of those only temporarily present and

on the place (address) at which each temporarily absent person can be found. is information

can be used for the purpose of allocating persons to the household (or institution) and geo

graphic area within which they are to be counted and of checking to be certain that no person

is counted twice (namely, at both the usual residence and the place where present). e proce

dures to be followed at the enumeration and through the subsequent allocation of persons must,

however, be very carefully planned and strictly adhered to if the allocation is to be accurate.

2.61. With the exception of mobile housing units (see discussion in paragraph 2.63), living

quarters and buildings have a ﬁxed location and therefore the place where they are to be enu

merated does not have, therefore, to be considered in taking a housing census. Information

on households, however, and the persons in households can be collected and entered in the

housing census questionnaire either where they are (or were) present on the day of the census

or at the usual residence. e procedure followed in the housing census should be governed

by that adopted in carrying out the population census if the two censuses are carried out

simultaneously. If the housing census is an independent operation, however, the procedure to

be followed should be carefully considered since it may have a signiﬁcant eﬀect on the validity

of the results of the housing census.

43Planning, organizing and management 43

2.62. Where persons and households are allocated to the place of usual residence, they

should also be allocated to the living quarters that they usually occupy. e living quarters

that they are actually occupying at the time of the census should be counted as vacant if

they are conventional dwellings, or they should be excluded from the census if they are non-

conventional dwellings.

2.63. Mobile housing units represent a special case as far as the place of enumeration is

concerned. ey should be enumerated where they are found on the day of the census; how

ever, in accordance with the procedure adopted for the allocation of the population, mobile

housing units may also be allocated to the area where the occupants usually reside, provided

that they are the usual living quarters of the occupants in the area of usual residence. Where

they are not the usual living quarters of the occupants in the area of usual residence, the

occupants will be allocated to their usual living quarters and the mobile housing unit will be

excluded from the census.

C. Enumeration point of time

2.64. One of the essential features of population and housing censuses is that each person

and each set of living quarters must be enumerated as nearly as possible with respect to the

same well-deﬁned point of time. is is usually accomplished by ﬁxing a census “moment” at

midnight at the beginning of the census day. is moment is the “census reference moment”.

2.65. For the population census, each person alive up to the census moment is included in

a census schedule and counted in the total population, even though the process of complet

ing the schedule does not take place until after the census moment or even after the census

day, and the person may have died in the interim. Infants born after the census moment are

not to be entered in a schedule or included in the total population, even though they may be

living when the other persons in their household are enumerated.

2.66. For the housing census, each set of living quarters that has reached an established stage

of completion and is not scheduled for, or in the process of, demolition should be included in

a census schedule and counted as a part of the housing inventory even though the process of

completing the schedule does not take place until after the census moment or even after the

census day, and the living quarters may have been scheduled for demolition in the interim.

Living quarters that have attained the prescribed state of completion after the census moment

are not to be entered in a schedule (unless special instructions are issued for recording living

quarters under construction), nor should they be included in the total number of sets of liv

ing quarters.

2 .67. Where the amount of time allotted for enumeration in the census is considered to be

so long that the population is not likely to be able to supply information as of a single moment

in the past, it may be necessary to employ diﬀerent points of time in the enumeration, even

to the extent of using the night before the visit by the enumerator. If such a procedure is

followed, it should be clearly explained in the census report and the total duration of the

enumeration should be stated. For ease of reference and for the computation of intercensal

indices, it is useful to designate a single date in the enumeration period as the oﬃcial “census

date”. is date could be, for example, the day by which half of the population was enumer

ated. is date is the “census reference (average) day” or, if reference is made to a period of

time, the “census reference period”. Another method could be to canvas the entire popula

tion before the census moment, and revisit every household within a ﬁxed number of days

immediately after the census moment to collect data on any changes that have occurred with

reference to the census moment.

To be considered as living

quarters, non-conventional

housing units and collective

living quarters are required to be

occupied in order to be included

in the census.

Principles and Recommendations for Population and Housing Censuses, Revision 344

D. Time reference period for data on the characteristics

of the population and of living quarters

2.68. e data collected about the characteristics of the population and of living quarters

should be pertinent to a well-deﬁned reference period. e time reference period need not,

however, be the same for all of the data collected. For most of the data, it will be the census

moment or the census day; in some instances (as is the case for current economic character

istics and rental arrangements), however, it may be a brief period just prior to the census or

(as is the case for fertility questions, usual economic activity and information on the period

of construction of the building in which living quarters are located) a longer period of time.

V. Legal basis

2.69. Legal authority for the census is required for regulating primary administrative

responsibility, for obtaining the necessary funds, for determining the general scope and tim

ing of the census, and for placing a legal obligation upon the public to cooperate and provide

truthful answers, a legal obligation upon the enumerator to record the responses faithfully,

and speciﬁc responsibilities upon other census ﬁeld personnel at various supervisory levels.

In addition, the conﬁdentiality of the individual information should be strongly and clearly

established in the census legislation and guaranteed by adequate sanctions so as to provide

a basis for the conﬁdent cooperation of the public. In countries that lack permanent legal

authority for the taking of periodic censuses, it is important to act early to establish ad hoc

legal authority or, preferably, legislation calling for a system of periodic censuses.

2.70. e principle of conceptual and organizational ﬂexibility should be observed in draft

ing the census legislation. e legislative provisions should ensure data security and conﬁ-

dentiality. However, the inclusion of provisions that are too rigid regarding the type of data

to be collected or the structure and relationships of the various parts of the census organiza

tion is undesirable. Rather, necessary details should be contained in the census regulations

promulgated by the census authorities. Moreover, provision may have to be made, in either

the legislation or the regulations, for sanctioning the use of simpliﬁed administrative proce

dures, including the appropriate delegations of authority for the procurement of equipment

and supplies and the recruitment of personnel during the operational phase of the census.

2.71. While the content of the census legislation will inevitably depend on national legal

practices and procedures, as well as on the organization of the national civil service, the

following components are usually represented: the purpose of the law; the coverage of the

census; assigning the mandate for conducting a census to a speciﬁc institution; the purpose of

the census; the obligations and rights of the citizens; the modes of ﬁnancing the census; the

organization of the census; administering the census; the rights and obligations of enumera

tors and supervisors; census data dissemination and exploitation; treatment of individual data;

conﬁdentiality and privacy of respondents and their data; and archiving.

2.72. A comprehensive and well-timed legislative framework is of utmost importance for

ensuring the legality and authority of conducting the census itself. In the case of an ad hoc

approach to the census legislation, that is, in the case where it is done before each census, it

often also contains the census topics clearly spelled out, thus providing additional legal weight

to the composition of the questionnaire and the content of the census.

45Planning, organizing and management 45

VI. Financial management

A. Financial basis for censuses

2.73. A census is the primary source of data about the size and characteristics of the popu-

lation; it provides a demographic proﬁle of a country and is the basis for developing area

sampling frames for use in surveys. A census, however, is usually one of the largest and

costliest statistical activities that governments and their national statistical oﬃces undertake.

As a result, countries have been forced to delay or even cancel a census owing to funding

constraints. Countries that have been able to secure partial funds or secure funds but at a late

stage of their census preparation have been forced to compromise their data collection, data

processing and dissemination of census results. It is therefore recommended that all census

operations, including planning, cartography, enumeration, processing, analysis and dissemi

nation, be budgeted from the beginning, and eﬀorts be made to mobilize the required funds.

Inﬂation should be taken into account, keeping in mind that duration has an impact on cost.

2.74. Hence, there is growing pressure to look into the solutions to census funding, taking

into account the role of key stakeholders, namely governments and their statistical agencies,

and the greater involvement of international donors and the private sector. Concurrently,

cost-eﬀective strategies need to be put in place that would reduce census costs without com

promising the quality of census data.

2.75. It should be emphasized, however, that censuses cannot be carried out merely by

national statistical and census oﬃces alone. Rather, conducting a census should be seen as a

national task involving all stakeholders. us, government departments, non-governmental

organizations and private sector end users should be consulted at all stages to ensure the

legitimacy of and need for conducting the census and, at the same time, to improve advocacy

for suﬃcient funding. Although conducting a census is principally ﬁnanced by the govern

ment, the census must be designed in partnership with all political actors so as to obtain their

involvement in the census process. A high-level committee consisting of the government,

the private sector and civil society, including non-governmental organizations, communities

and donors, could be formed to discuss issues related to the cost and funding of the census.

2.76. National statistical and census oﬃces need to advocate the importance of investing in

censuses within their own governments. It is also important for the national statistical and

census authorities to ensure continuous feedback and promote the use of statistical data from

previous censuses, in order for users to recognize the importance of the population census

as a source of vital statistical data and give their support. e possibility of cost sharing with

other government departments, such as education and health ministries, should be further

explored. ese institutions could be supportive in providing logistics arrangements for the

census, such as the use of existing infrastructure, transportation and communications facili

ties, and sharing of employees of other government departments.

2 .7 7. Good planning is essential not only for achieving a cost-eﬀective census (see para

graph 2.11) but also for securing comprehensive ﬁnancial support for its funding. Technol-

ogies and methods that will be used in mapping, data collection and processing, question

naire design and other activities must be decided upon in advance, as these have an inﬂuence

on costs. Census planning must bring out the links between the various components, which

will include types of resources (such as personnel, cost of stationery or printing) and tasks

(including data collection and capture, data processing, and data management and dissemi

nation). Cost tags must be attached to each of these components together with a justiﬁcation.

Experience from past censuses or similar activities must be considered when estimating costs

for the next census. Where multiple modes of data collection and new technologies are being

used for the ﬁrst time, these must be tested for data quality and cost implications.

Principles and Recommendations for Population and Housing Censuses, Revision 346

2.78. For each stage of the census the costs must be optimized. A careful choice of the

appropriate technology will greatly assist in this. Recent advances in technologies throughout

the census process, such as digital mapping, computer-assisted or Internet data collection,

scanning, data processing and data management and archiving, and census data analysis

and dissemination, may be of assistance in achieving signiﬁcant reductions in cost (or doing

more within the same cost). In addition, the proper selection and use of such technologies will

speed up the computation of results and enhance their preservation. However, the choice of

technology should be made only after carefully evaluating the costs and beneﬁts of possible

options. Some potential risks to canvass include the following: some approaches only become

cost-eﬀective for large operations; some are dependent on expensive and scarce inputs (for

example very high-quality satellite images or paper for scanning); some are dependent on

services that may not be available throughout the country (for example Internet access); and

others require signiﬁcant investments in high-quality computers and upfront investment in

human resources. e options examined in the cost-beneﬁt analysis could incorporate con

sideration of leasing (rather than purchasing) equipment or sharing it between countries that

are undertaking censuses at convenient times.

2.79. Outsourcing to the private sector could be considered as another cost-saving option,

particularly in the context of publicity or for systems development for data collection, pro

cessing and dissemination. Outsourcing can contribute technical expertise or resources not

readily available within the national statistical oﬃce.

2.80. It is anticipated that international donors will continue to play a pivotal role in helping

to fund census costs in many countries. Technical cooperation and assistance from interna

tional agencies have also contributed greatly to the success of censuses in many countries. It

is worth noting that a population and housing census has some intangible positive values. It is

an opportunity for mobilizing the whole country and reaching even the most remote corners

of it. In the life of many citizens, a regular census is often the only time that the State reaches

out to them and asks them some questions. Successfully conducting a census is a matter of

pride in many countries and a welcome opportunity to recruit a massive labour force and

generate jobs and train people in valuable tasks (such as data entry) or in other ways to add

to the national infrastructure.

2.81. In general, population and housing censuses are exclusively the responsibility of

national governments and structures; this is particularly true for funding the census. us,

all activities related to funding need to be elaborated, documented, justiﬁed and presented

to all stakeholders in a transparent and comprehensive manner.

B. Budget and cost control

2.82. While no universal system of census budgeting and cost control can be suggested

since ﬁnancial practices vary greatly among countries, a few generally accepted principles can

be noted. First and foremost, eﬀective planning and control of the various census operations

are not possible without a very careful ﬁnancial estimate of the cost of each census operation,

including all of its components, no matter how small. It is recommended to draft a detailed

list of activities related to censuses and, as much as possible, to draft the budget in such a way

that it corresponds to this list of activities. Second, it is critical for this census plan and budget

to be presented by national statistical and census agencies to their respective governments

with adequate lead time, to facilitate the appropriation of suﬃcient resources from national

budgets or, where required, from the international development community. Moreover, fund

ing of the census must be accompanied and developed on a sound and adequate legal basis if

eﬀective national census operations are to be enabled.

47Planning, organizing and management 47

2.83. Information on expenditures from the previous census, classiﬁed by census phases,

starting with the expenditure for diﬀerent elements of the preparatory work and ending with

expenditure for the dissemination of the census results, provides an important basis for esti

mating the budget of the census. Figures from the previous census will of course have to be

reviewed and modiﬁed in order to take into account quantitative and qualitative changes in

hardware and software, changes in wage rates and the costs of equipment, supplies and so on,

planned changes in census content, methods and procedures, and anticipated changes in the

population itself (for example, total size, percentage urban, and average household size), all

of which may aﬀect the cost structure of the census. In most countries, several cost elements

tend to increase (for example, wage rates and the size of population) so that there is consider

able pressure to achieve economies in other items of the census budget.

2.84. e census oﬃces need to implement transparent accounting procedures and ﬁnancial

management systems to ensure speedy disbursement of funds, proper receipting of expenditures

and an eﬃcient audit. is would enable prompt release of periodic allocations of census funds

by national governments. A clean outcome from a ﬁnancial audit adds credibility to the census

process so that the government and civil society are more likely to accept the ﬁnal results.

2.85. In the case of external or donor funds, the required conditions should be established

well in advance by discussion between the donor and the national statistical or census oﬃce.

is will avoid delay in the release of such funds for census operations.

2.86. Control measures and monitoring systems must be developed for cost-eﬀectiveness.

Activities to be outsourced must be clearly deﬁned and contracts for outsourcing should be

well prepared with clear deliverables and timelines.

2.87. For planning the costs of a census, detailed and precise data will be required on the

following: (a) number and cost of census staﬀ classiﬁed by function and manner of payment;

(b) type of equipment and material used for the census, manner of acquisition (purchase or

rental) and cost; (c) oﬃce space (surface measurement), classiﬁed by use and type of cost (that

is, for construction or for rent); and (d) type of services used for census operations. e use

fulness of the above information would be enhanced if the information could be recorded by

source of funding, in other words, in terms of whether the expenditure has come from (a) the

oﬃcial census budget; (b) other funds of the census oﬃce (for example, a regular annual

budget not speciﬁcally intended for census purposes, or general funds of the governmental

agency or department of which the census oﬃce is a part); (c) other parts of the government;

(d) non-governmental organizations; or (e) international donors. is information is needed

not only for ﬁscal planning and control but also in order to examine the trade-oﬀs in terms of

costs and beneﬁts among alternative ways of carrying out various census operations. Although

cost experience from a previous census in a country may provide useful experience for plan

ning the next census, much more caution should be exercised in using the cost parameters

from other countries. Diﬀerences in census content, organization and operations, as well as

in cost accounting, can introduce serious incompatibilities into such country-to-country cost

comparisons.

2.88. It is important that the persons at the administrative and supervisory levels who will

be responsible for the execution of each operation participate in estimating the budget items.

Such an organization of the work presupposes detailed advance planning and “cost conscious

ness” on the part of those responsible for a census.

2.89. e census plan as executed will certainly change in a number of respects after the

making of the original calculations. Consequently, a perfect correspondence between the

estimates and the ﬁnal costs is not to be expected. Changes in the prices of major components

of census costs should be monitored on a regular basis with either the census budget adjusted

accordingly or the census plans modiﬁed. Indeed, the development of the census budget is

See United Nations Economic

Commission for Europe, Measur-

ing Population and Housing:

Practices of UNECE Countries

in the 2010 Round of Censuses

(NewYork and Geneva, 2014).

Principles and Recommendations for Population and Housing Censuses, Revision 348

usually an incremental process in which rough initial estimates are replaced by more detailed

and precise statements of resource requirements. roughout the period of census taking

and compilation of census results, the budget will have to be re-examined and performance

compared with plans. With detailed information on expenditure, the governmental and cen

sus authorities will be better able to exercise control over keeping the development of census

operations within the census budget and to assess and control the eﬀectiveness and eﬃciency

of these operations. is information is also very useful for studying possible improvements

in census techniques and census methodology.

2.90. As with any project, particularly ones as large and complex as the census, it will not

go according to plan and there will be diﬃculties. Accepting this at the outset and making

sure there are arrangements in place to deal with delays, changes or other unforeseen issues

is essential. In particular, there must be resources set aside to enable such issues to be dealt

with quickly. erefore some contingency funding should be included within the overall

costs of the census, and some controls put in place to monitor and allocate the contingency

pot. Diﬀerent methods exist for estimating the cost of the contingency budget, such as risk

modelling, but a good starting point might be to allocate a percentage of the annual budget

(say 15 per cent) each year for such contingency.

VII. Administrative organization

A. Overall overview

2.91. In planning the organization and administration of a census, it is important to consider

the role and relationship of the various executive and advisory organs. National, subnational

and local commissions and committees are frequently useful in the planning and prepara

tions of a census. Such bodies may be composed of representatives of governmental agencies,

community leaders with due representation to all sections of society, and non-governmental

users of the census data, particularly those involved in policy-oriented analysis of census results

and analytical studies of the social, economic and demographic situation of the country. is

ensures broad-based and complete participation of the people to enable proper canvassing of

sensitive issues such as ethnicity, gender, disability, migration, and marginalized groups. It is

important, however, that their advisory and promotional functions be clearly deﬁned and that

the ﬁnal responsibility for planning and execution rest with the executive agency.

2.92. ere are well-documented and proven advantages in having an oﬃce continuously

responsible for census work established as an integral part of the statistical system of a coun

try. Such an oﬃce assures continuity in census work and is the principal centre for the

formulation of the programme and the initiation of preparatory work for the next census.

Its permanence permits the development of specialized and experienced personnel and the

maintenance of statistical and cartographic information, including cross-cutting issues such

as information technology, essential for planning the next census.

2.93. At the pre-enumeration stage, the census oﬃce will need to be expanded to form the

nucleus of the full census organization, which must be capable of directing the ﬁeld organiza

tion during the preparatory work as well as during the enumeration and processing. In order to

provide immediate supervision in each area, ﬁeld oﬃces at various levels are needed for the later

part of the preparatory work, including staﬀ recruitment and training, as well as for the enu

meration period. Supervisory personnel in such oﬃces should be persons who, being familiar

with the particular area and the local language, are able to deal with local problems. is does

not mean, however, that all supervisory positions need necessarily be ﬁlled by persons from the

49Planning, organizing and management 49

area. Personnel may be transferred from the central oﬃce or from other areas as the need arises.

Prior training of all such available personnel is necessary, so that they have a working knowledge

of all aspects of the current census programme. An essential part of the preparatory work is local

administrative planning, which would set out the likely problems and challenges speciﬁc to the

local area and how they are to be dealt with. Adequate coord ination with local public authori

ties is always important so that the enumeration work is not interrupted due to other activities.

2.94. Subsequent to the enumeration, the census organization is usually readjusted to meet

the needs involved in compiling, evaluating, analysing and publishing the results and to

provide the continuity desirable for promoting the continued use of census materials. Cen

sus organizations need to pay special attention to continuity of knowledge and skills from

one census to the next, since the intervening gap, which is usually a whole decade, is likely

to cause loss of institutional memory and attrition of qualiﬁed personnel. Comprehensive

documentation of census activities while they are being carried out is essential, as is training

of younger personnel to create a pool of knowledgeable and experienced persons by the time

the next census comes.

B. Statistical leadership

2.95. e period of preparation for the population and housing censuses represent a unique

opportunity to exercise leadership in promoting the use of statistics in overall development

of societies, with the focus on improving service delivery and policy development. Statistical

leadership needs to be built and should rely on international standards and guidelines, such

as the Fundamental Principles of Oﬃcial Statistics,

on national statistical legislation and on

the national statistical code of ethics.

2.96. An important role of the head of the national statistical oﬃce or statistical agency

responsible for census undertaking is to ensure a successful census programme that delivers

results for use in evidence-based policy development, evaluation and research, and decision-

making. It is therefore recommended that heads of national statistical oﬃces or statistical

agencies responsible for census undertaking drive the following activities:

(a) Establishing statistical legislation that mandates the undertaking of a census;

(b) Setting policy and strategy by deﬁning targeted outputs and outcomes for the

programme;

ernment, business and the public at large;

(d) Raising the proﬁle of and commitment to use statistical information, providing

an opportunity for engagement on key policy issues and strengthening relation

ships between information providers, policymakers and opinion leaders;

(e) Adhering to the Fundamental Principles of Oﬃcial Statistics and ensuring best

practice is embedded in statistical procedures;

(f ) Aligning to international standards and frameworks;

(g) Establishing statistical infrastructure and resources for undertaking the census;

(h) Setting up the census management project structure.

2 .97. Preparing and conducting a population and housing census oﬀers the opportunity to

exercise statistical leadership by promoting oﬃcial statistics and their use for development at

all levels of society. As the census usually takes place only once in a decade, there is a need to

carefully take advantage of this event in terms of exercising statistical leadership to the full

est extent possible under the understanding that statistics are numerical facts for statecraft.

Adopted by the Economic

and Social Council of the

UnitedNations, available from

http://unstats.un.org/unsd/dnss

/gp/fundprinciples.aspx.

Principles and Recommendations for Population and Housing Censuses, Revision 350

VIII. User consultation, communication

and publicity

2.98. A comprehensive programme of communications for a population and housing census

covers three distinct audiences: (a) major users of census data, (b) persons and institutions

participating in the census operations and (c) the general public. Since the census is a national

activity that is completely dependent for its success upon the wholehearted cooperation and

assistance of the general public and many governmental and local organizations, the entire

communications eﬀort should be developed as a coordinated activity in close conjunction with

the other substantive preparations for the census. ese communications activities are valu

able not only for informing others about the census but also for providing census authorities

with early and continuing information about the reactions to census plans and activities of

the general public in various parts of the country and of key persons, groups and institutions.

2.99. Consultation with users of census data on topics, on deﬁnitions and, particularly, on

planned tabulations and other outputs and the development of the census database is an indis

pensable step in the preparations for the census that should be taken early. ese consultations

will assist the census authorities in planning for a census that, within the resources available,

is as responsive as possible to user needs in terms of the collection, processing, tabulation,

storage and availability of meaningful statistics. Such consultations can also serve to foster

a wider and more informed understanding of and support for census plans and activities.

e users to be consulted should be from governmental departments, ministries, universities

and other research institutions, the private sector and other organizations (or individuals)

representing the economic, social, educational and cultural life of a country. Many countries

will want to include in the groups to be consulted organizations or bodies representing ethnic

communities, religious and faith groups, persons with disabilities, housing associations and

those agencies with particular interests in catering to the homeless. Other key stakeholders

may include partners with whom the census oﬃce collaborates for the provision of specialist

services, and donors who may help fund elements of the census operation.

2.100. Taking into account the importance of the census in providing data for local planning

and administration, it is also often advisable to have consultations with users in provincial and

local governments and institutions in various parts of the country. Particularly in large coun

tries or countries where the provincial or local governments have a comparatively high degree

of autonomy, consultation with users at the subnational level is essential if the full potential

of the census is to be achieved. Strategies should be chosen according to the target group.

2.101. e consultation process can take many forms. If done in the form of meetings, it is

often more useful to hold separate consultations with diﬀerent types of users with common

interests, such as administrators, policymakers, planners, demographers, researchers, users in

the business community and so forth, rather than a simultaneous consultation with all data

users. Consultations involving diﬀerent types of stakeholders in the same setting frequently

prove frustrating to participants because there are substantial diﬀerences among users in their

technical background and in their concern with the details of census content and operations.

2.102. Meeting data users is very informative but imposes physical and budget limitations.

Broad consultation can be implemented on the website of the census oﬃce or government.

e strategy can be used both to collect suggestions from users and also to provide transpar

ency in the census preparation activities. Other forms of technology can be considered to

hold decentralized or remote consultations. Users may be sent an electronic questionnaire to

collect their priority information requirements, or invited to complete the questions online.

51Planning, organizing and management 51

Social media may need to be taken into consideration in this respect, as they reach a sub-

stantial number of users.

2.103. In order to complete the preparatory work for the census and to carry out the census

enumeration itself, the census oﬃce will have to expand its staﬀ substantially. In addition,

numerous governmental and non-governmental organizations outside the census oﬃce may

be called upon to provide personnel, equipment, supplies, space, transportation or commu

nications facilities and so on to help in the census work. As a result, large numbers of tem-

porary personnel will have to be trained (see paragraphs 2.119-2.124) and the contributions

of a diverse group of national and local organizations will have to be eﬀectively mobilized.

A well-planned communications programme can contribute to both eﬀorts.

2.104. An eﬀective communications strategy, together with far-reaching publicity and infor

mation campaigns, play an essential role in ensuring the success of the census. is is espe-

cially so for those countries adopting a ﬁeld enumeration methodology, either wholly or in

part, where the general public is expected to actively participate in the census activities as

respondents and, possibly, as temporary employees either as part of the ﬁeld staﬀ or in the

data-processing operation. Particularly in the case of countries that undertake a signiﬁcant ﬁeld

operation, public acceptance and cooperation is essential to ensure the success of the census.

A large-scale publicity and information campaign is recommended to inform the population

of the census and to explain its purpose. Implementation of the publicity programme is best

undertaken by experts in the ﬁeld of public relations, advertising and sociology. Such exper

tise is frequently not found within the national statistical oﬃce itself, and it may therefore

be appropriate to outsource some or all of this work. e publicity programme may include:

(a) A public relations campaign;

(b) A community liaison (or outreach) programme;

(d) Monitoring of public opinion;

(e) Media relations, including monitoring of the mass media.

2.105. ere are several main messages that census agencies will need to communicate to

the public in order to maximize outcomes for the census. Census publicity campaigns should

encompass a wider set of messages, whose components might include (a) making the public

aware of the census; (b) educating the public about the beneﬁts (to them and to the country)

of the census; (c) reminding people about their legal obligation and duty to take part in the

census; (d) explaining to the public what to do and when; (e) informing the public that pri

vacy and conﬁdentiality will be protected; and (f ) expressing thanks to the public for taking

part in the census. Care is necessary in ﬁnding the correct balance between these diﬀerent

messages. For example, an overemphasis on the obligatory nature of the census may serve to

reinforce negative perceptions that the census is an imposition by the State on the population,

rather than an activity for the common good.

2.106. Publicity for a census operation entails an educational campaign, the purpose of which

is to enlist the interest of the general public and its cooperation. e aims, as a general rule,

are not only to dissipate any anxiety regarding the purposes of the census but also to explain

the reasons for the various questions in the questionnaire and to oﬀer some guidance as to the

manner in which these questions should be answered. e publicity campaign may also be an

important tool for increasing the completeness of census coverage, particularly among hard-

to-enumerate groups. It is desirable that planning for the general publicity campaign should

start as soon as the census is authorized. e campaign itself should be closely synchronized

with other census activities and full-scale publicity should not begin too far in advance of the

date on which enumeration is scheduled to start. Plans for the publicity programme should

Principles and Recommendations for Population and Housing Censuses, Revision 352

be closely coordinated with those for the census tests (see paragraphs 3.110-3.114). e pro-

gramme will have to provide the publicity needed to carry out the census tests. In addition,

the programme can use these tests to study the impact of alternative publicity materials and

methods. If either the cartographic or house-listing operations require extensive ﬁeldwork

and widespread contacts with the public, it should be recognized that personnel involved in

these activities often provide the public with its ﬁrst impression of the census. Training and

publicity programmes should take this factor into account.

2 .107. e general campaign should be directed to all sections of the country and all seg

ments of the population through the use of all available publicity media, with special empha-

sis on the use of contemporary Internet-based social media. e general campaign may be

supplemented by a number of specialized campaigns aimed at speciﬁc segments of the popu

lation to sensitize on speciﬁc subjects, such as gender, migration, ethnicity and disability, in

which the quality of response may depend on the level of prior sensitization in the general

public. In multilingual countries, creating campaigns in the local languages is crucial. Apart

from national and local mass media, such as newspapers, television and radio, the use of

interactive media, such as a toll-free helpline, social media such as Facebook and Twitter, short

messaging service (SMS), multimedia messaging service (MMS) and local events where the

public can participate, go a long way towards improving public awareness and building trust.

2.108. Disseminating information about the rationale of the census and its utility helps

alleviate possible misconceptions among the general public, thus increasing participation and

coverage. Media advisories issued by the statistical oﬃce will usually be widely covered by

the media at no cost. Outreach campaigns involving diﬀerent organizations and enlisting the

support of local leaders and opinion makers to spread the word about the census in their area

of inﬂuence is also a good strategy. In addition to recruiting such organizations and leaders as

partners, the census organization may develop key messages, web buttons, posters and other

material to support them in their activities. e use of publicity may also be considered to

support the recruitment of ﬁeld personnel.

2.109. Many countries successfully develop a census “brand”, including a logo and slogan.

A simple but eﬀective slogan and distinct logo can be used in all national and local advertis

ing campaigns and in all types of media, booklets, posters, brochures and souvenirs. e

slogan and logo should be memorable and positively perceived. A slogan and logo that are

well recognized from the initial stages of the publicity campaign may serve to improve “brand

recognition” for the census. e aim should be to encourage the respondent to feel more reas

sured that the census is an inclusive and beneﬁcial activity.

2.110. Special attention is often given to identifying and targeting hard-to-reach population

groups in order to ensure consistent levels of response across the country. In essence, the aim

of these is to engage, educate, explain and encourage, and (if necessary) to enforce participa

tion. Students (particularly older students living away from home), young men (particularly

those in urban areas), older persons, the inﬁrm or persons with disabilities, and recent immi

grants are among population groups that are generally hard to enumerate. Other groups that

may need to be specially targeted included the homeless, people with literacy and language

diﬃculties, and inhabitants of inner cities and dense urban areas.

2.111. In rural areas, weekly markets, fairs and public festivals are a good opportunity to

publicize the census message among people who may not have much exposure to mass media.

An excellent opportunity exists to create widespread awareness of the census through a cam

paign targeted at schools. Other kinds of local-level publicity, such as wall writing and village

announcements, can be planned according to local circumstances.

53Planning, organizing and management 53

2.112. Census organizations should monitor public opinion and the mass media to assess

the eﬀectiveness of publicity campaigns. Public opinion could be monitored through sur

veys that can provide information on public attitudes to the census. Monitoring of mass

media involves an analysis of mass media publications concerning the issues of the census,

and particularly the extent to which diﬀerent population groups have been targeted. It is

an ongoing accumulation of information, detection and prevention of the development of

negative published comments on the census, and preparation of adequate answers to nega

tive reports and information. Increasingly the media has a signiﬁcant inﬂuence on people’s

behaviour and even minor distractions and mistruths can have a detrimental eﬀect on the

outcome of the census. erefore, in developing their publicity campaigns, national statistical

oﬃces should give particular attention to preparing for unexpected events (such as negative

attitudes, malicious lobbying, technical diﬃculties, delays and misleading information). It is

also recommended that all oﬃcial participants involved in census operations know their roles

in the communication process both with the media and with the public at large.

2.113. An integral part of census communication and publicity is informing key census data

users and the general public about the availability of the census results and their utility (see

paragraphs 1.19-1.37). Awareness about census data and utilization should be done during

the intercensal period before the commencement of the next census. is is to make sure that

the public recognizes the importance of the census and appreciate statistics that are generated

from it. It is critical that such communication strategies be developed as an integral part of

census planning and not left as an optional add-on. It has been the experience of quite a few

countries that the engagement of professional media and communication personnel adds

value to the campaign.

IX. Census calendar

2.114. An indispensable element in the planning of a census is a calendar or timetable indi-

cating the sequence and estimated duration of each of the component operations of the cen-

sus. At the early stages of census planning, a provisional calendar of selected key dates should

be prepared as an overall framework for the census. e calendar must be shared with stake

holders in advance for advice and support. e calendar should be revised and made more

detailed as planning proceeds, with the aim of establishing ﬁnal dates as soon as practicable.

2.115. Such calendars are essential, since they indicate the dates on which each of the numer

ous operations that make up a census are to be started and completed, and they serve as a

guide for measuring the progress of each stage of the census operation. Serious delays in work,

or errors in time estimates, can be detected by comparing the calendar target dates with the

actual dates of each operation. A census calendar is a very eﬃcient instrument not only in the

timing control of each census operation but also in the control of the complex of all census

operations that are interdependent. erefore, when modiﬁcations in the census timetable

are necessary, all related operations should be taken into consideration in order to avoid dis

ruptions in the whole census programme. Obviously, the time schedule will diﬀer for each

national census depending upon the general census plan and the resources that are available.

2.116. e census calendar usually shows the various operations grouped into three broad

sectors: (a) pre-enumeration, (b) enumeration and (c) post-enumeration. e last-named sec

tor includes evaluation and analysis as well as processing and dissemination. e basic date

on which the census calendar and the scheduling of all other operations hinge is the starting

date for the general enumeration of the population. For purposes of control, many operations

that in fact overlap are shown separately in the calendar. Census calendars sometimes take the

Principles and Recommendations for Population and Housing Censuses, Revision 354

form of a chart or graph, in addition to a detailed checklist of operations. Project management

software may help in the preparation of the census calendar.

2 .117. In establishing the census calendar, it is necessary to consider the relationship of the

population and housing censuses to one another as well as to other statistical projects or other

large-scale national activities. Although a joint population and housing census operation is

likely to constitute, for the period of its duration, the major statistical undertaking of the

government, care should be taken that it does not interfere unduly with the other regular

statistical activities that may be going on at the same time. A balanced statistical programme

should avoid having too many simultaneous competing enquiries, which might place too

heavy a burden on the statistical services and on the public, with a possible resultant loss of

both administrative eﬃciency and public cooperation.

2.118. It is often useful to draw up a comprehensive diagram showing the sequence, inter

relationship and timing of all the various steps in the census programme—a Gantt chart

would be a good example.

is type of analysis often reveals the consequences of a delay

at one step in terms of delays at other steps in the programme. It can therefore be a use

ful instrument against which the actual progress of census preparations may be compared.

Indeed, some countries have attempted to use such critical path analyses not only as an aid

to census planning but also as a tool for the ongoing management of their census operations.

In these instances, it is essential to establish procedures for revising the critical path analysis

in response to actual progress. It should be stressed, moreover, that the usefulness of such

devices depends on how soundly they are designed, applied and understood. Project manage

ment software can be useful in linking the diagrammatic structure of census operations with

information about nodes or centres of responsibility for individual broad or detailed opera

tions so as to control the chain of responsibility. Alternatively, event calendars can provide a

broad view of the steps of the census programme and allow follow-up. Diﬀerent tools can be

found on the Internet for download or online use. Online versions allow immediate update

and make it easier to work in a group, but are dependent on Internet access. Other tools,

commonly referred to as groupware and collaboration software, as well as Internet and social

media forums, can support census operations by providing an environment for exchange of

information, ﬁles and data among dispersed teams.

X. Human resources management

2.119. Early arrangements are necessary to secure the proper number and type of personnel

required for each of the various census operations. For reasons of eﬃciency and economy, it

is important that the staﬀ be selected on the basis of competence. Consideration may also

be given to the use of the same staﬀ for successive operations, thus reducing the turnover of

personnel. While the preparatory and processing work generally calls for oﬃce employees

possessing or able to learn certain specialized skills (cartographers, coders, data entry opera

tors, programmers and so on), the enumeration stage usually demands a large number of

persons capable of going to their assigned urban or rural enumeration areas and collecting the

information according to speciﬁc deﬁnitions and instructions. e number of enumerators

required being quite high compared to normal staﬀ strengths, and the period for which their

services are needed being rather short, the method of recruiting them needs to be worked

out carefully in advance to facilitate quick, simultaneous and transparent hiring, and sub

sequently compensating them and relieving them of their duties promptly and eﬃciently.

Consideration should be given to computer skills if electronic means of enumeration are going

to be used. It is essential that the enumerators and, to the extent possible, their immediate

supervisors be conversant with the languages or dialects of the area in which they will be

The Gantt chart was developed

around 1910 by Henry Gantt

of the United States, based on

the work of Karol Adamiecki of

Poland. It is a type of bar chart

that illustrates a project schedule

and is available in a number of

oﬃce software packages.

55Planning, organizing and management 55

working. In addition, attention should be paid to physical ﬁtness, ability to read maps and

communication skills in general. It is only prudent to recruit and train suﬃcient reserves to

take care of any attrition that may occur in the process.

2.120. Once the cartographic preparations are substantially complete and the questionnaire

has been sent for printing, perhaps the single most important means that the census authori

ties have for inﬂuencing the success of the census is the training programme. e contribution

that a well-planned and executed training programme can make to the quality of the census

results cannot be stressed too strongly. Such a training programme must of course focus on

the widely dispersed and diﬃcult-to-supervise ﬁeld staﬀ (namely, the enumerators and their

immediate supervisors) but it must also cover others (for example, the higher-level supervi

sors, editors, coders and computer operators). Giving all oﬃce employees who are working

with the census preparations a brief, uniform basic training on all aspects of the census has

two prime advantages: ﬁrst, all personnel understand the importance and the context of their

part of the task; and second, since they are conversant with the basics, they can be swiftly

deployed in the ﬁeld for supervision or coordination during the actual census operations

whenever and wherever needed.

2.121. e entire census training programme should be designed to cover each phase of the

work and provide an eﬃcient and consistent means of eﬀectively equipping large numbers

of fresh employees with the necessary skills. e programme will need to correspond closely

to the needs of the various operations and, where appropriate, may include both theoretical

and practical instruction, with emphasis on the latter. In the case of the enumerators and

their immediate supervisors, the training is most eﬀective if it includes several opportunities

for the trainees to participate in practice interviews and role-playing exercises, including the

use of adopted IT solutions, if any. In countries in which multiple languages are used, the

method and content of the enumerator training programme will need to be suitably adjusted.

For example, if the questionnaire is printed in another language, provision will have to be

made for instructing enumerators on the correct formulation of the census questions in the

vernacular. Enumerators and supervisors should be trained as close to the ﬁeld operations as

possible so as to avoid recall lapses. is leaves very limited time for conducting the training.

erefore, the logistics need to be worked out carefully in advance. e training programme

for editors, coders, operators of data recording equipment and so forth should also provide

opportunities for the trainees to practise under the supervision of the trainers. e intermedi

ate- and higher-level technical staﬀ, such as programmers and system analysts, should also

be given special training with emphasis on recent technical developments of relevance to the

forthcoming census and on the interrelationships among the various aspects of census plans

and operations. orough training in census practices is an extremely important component

of quality assurance. Detailed and clear documentation of instructions with appropriate illus

trations is a basic requirement in this regard. A proper training methodology and a variety of

training aids would go a long way in enhancing the training eﬀort.

2.122. e organization and conduct of training courses should be entrusted to those having

the necessary qualiﬁcations to carry out this task successfully, taking into account not only

their professional abilities but also their ability in teaching. is means that staﬀ in charge

of training should have certain qualiﬁcations that will enable them to stimulate the interest

of trainees and to transfer the required knowledge, since otherwise well-qualiﬁed technical

personnel who are unable to transfer their knowledge to the trainees in a satisfactory manner

will be unsuitable as instructors for group training activities. is must be taken into con

sideration when selecting instructors, and it is recommended that objective criteria should be

used. In practice, however, it is diﬃcult to ﬁnd the necessary number of instructors who have

both the professional and the teaching qualiﬁcations; for this reason, the instructors selected

should themselves undergo training in how to organize and conduct training courses. e

Principles and Recommendations for Population and Housing Censuses, Revision 356

use of professionally designed training guides can add immense value to the training eﬀort.

e involvement of experienced professional experts in the design and delivery of training

programmes is also very useful. It should however be noted that the content should be the

responsibility of the census authorities and not that of outside experts.

2.123. It is important that training manuals for each training programme are made available

to the census organizers and training instructors. Such a manual would be a valuable guide

and would help considerably in the eﬃcient training of census staﬀ. It would also contribute

to the uniformity of training, which is an essential factor for a successful enumeration, taking

into account the great number of census instructors who will be engaged in training. Simple

audiovisual aids (for example ﬁlm strips, posters, compact disk recordings) can also be used

to help make the training more eﬀective and uniform throughout the country. If available,

new multimedia technologies can facilitate the provision of training at distant locations (dis

tance learning) and be eﬀective and eﬃcient supplementary tools for training. Standardized

training may also be provided in e-learning format on the Internet and on handheld devices.

2.124. It is very important to determine the time required to train staﬀ for the various

aspects of the census. is depends on several factors, such as the task for which they are

being trained, the complexity of the content, the educational level of trainees, the number

of instructors available and the funds available. Apart from ﬁxing the number of days for

training, it is also important to allocate appropriate time for each subject. Drawing up lesson

plans for each session of training is an eﬀective way of ensuring that all subjects are covered,

with the right amount of time being devoted to each.

XI. Logistics management

2.125. A population and housing census diﬀers in many respects from other statistical opera-

tions. It requires eﬃcient communication between many diﬀerent components, including

the procurement operation and storage of a large variety of items, most of which have to be

distributed to all geographic areas of the country and then recollected.

2.126. Logistics management is a process of planning, implementing and controlling the

ﬂow of census materials and equipment needed for implementation of census operations.

Logistics planning requires careful coordination between diﬀerent phases of the census opera

tion, such as mapping, training, ﬁeld enumeration, data processing and dissemination. e

scope of the logistics programme usually diﬀers from one country to another, but mostly

covers the following activities: (a) renting central and ﬁeld oﬃces; (b) installing furniture

and equipment; (c) providing help desk support; and (d) delivering and collecting all census

materials, including manuals, questionnaires and publicity materials.

2 .127. National statistical oﬃces may need to establish a special team for planning, imple

mentation and controlling the logistics programme. e functions of this team should be

clearly determined in order to avoid overlap or omission of any activity. During the planning

phase of the logistics programme, outsourcing of some activities should be carefully examined

as an option.

In the context of census logistics, procurement plays a particularly important

role throughout the whole exercise.

A. Procurement management

2.128. Developing a strategic approach to procurement is another particular element for

successful implementation of a census operation. Taking into consideration the complexity

For a detailed discussion on

outsourcing of census activities,

see paragraphs 2.140-2.154.

57Planning, organizing and management 57

of the process, procurement planning requires logistical coordination with multiple census

activities and counterparts. Proper planning contributes to eﬃcient procurement processes

and reduces the risk of confronting problems that may lead to additional costs and delays.

Procurement planning is a complicated exercise and emergency work and last-minute opera

tions are usually unavoidable. However, the beneﬁts of procurement planning early in the

census operation usually outweigh the disadvantages.

2.129. In the context of censuses, procurement planning entails the process of assessing and

projecting the procurement needs of census operations. Needs assessment, cost estimation

and requirement deﬁnition are the ﬁrst steps in the procurement process, and are essential

components in procurement planning. e purpose of requirement deﬁnition is to identify

the precise needs of the census operation and to search for the best solution to meet those

needs. e needs must be described in the requirement deﬁnition in a way that will facilitate

the procurement process. e requirement deﬁnition is often done in parallel with supplier

sourcing and market research in order to let information from the market research inﬂuence

the requirement deﬁnition.

2.130. Procurement practices vary greatly among countries; therefore, no universal system of

procurement management can be suggested. However, a few generally accepted procurement

principles can be noted. First is the principle of best value for money. Best value for money

represents an optimal combination of technical and ﬁnancial attributes—that is, the balance

between price and performance that provides greatest overall beneﬁt under the speciﬁed

selection criteria. is does not necessarily mean selecting the lowest initial price option, but

rather represents the best return on the investment, following a proper evaluation of oﬀers

under appropriate criteria contained in the solicitation documents. It requires an integrated

assessment of technical, commercial, organizational and pricing factors in light of their rela

tive importance. Best value for money can include non-cost factors such as ﬁtness for purpose,

quality, service and support, as well as cost-related factors such as price, life cycle costs and

transaction costs associated with acquiring, using, holding, maintaining and disposing of

the goods or services. e principle of best value for money should be applied throughout

the procurement process in order to attract the oﬀer that most eﬀectively meets the stated

requirements of the census operation.

2.131. Second is the principle of eﬀective competition. Eﬀective competition is best explained

as a situation in which at least three independent contractors acting on their own (that is,

not in collusion with each other) eﬀectively compete for the same business opportunity and

each submit a responsive bid. e procurement processes should foster eﬀective competition

as a means of ensuring fairness, integrity, transparency and achieving best value for money.

e competitive process should, as necessary, include (a) procurement planning for develop

ing an overall procurement strategy; (b) market research for identifying potential suppliers;

and procedures relating to procurement; and (d) formal methods of solicitation, utilizing

invitations to bid or requests for proposals on the basis of advertisement or direct solicitation

of invited suppliers; or informal methods of solicitation, such as requests for quotations.

2.132. Another important principle is fairness. e manner in which the procurement process

is carried out must give all stakeholders the assurance that the process is fair. e concept of

fairness includes that the procurement process should be free from favouritism, self-interest

or preference in judgment. e assurance of a fair process promotes transparency, a princi

ple that ensures that timely information about existing conditions, decisions and actions

relating to procurement activities and about procurement policies, procedures, opportunities

and processes are clearly deﬁned and made known simultaneously to all interested parties.

A transparent system has clear rules and mechanisms to ensure compliance with those rules.

Principles and Recommendations for Population and Housing Censuses, Revision 358

A transparent system of procurement further ensures that procurement records are open, as

appropriate, to inspection by auditors. In line with the procurement principles of transpar

ency, every step in the procurement process should be documented and kept on ﬁle, preferably

electronically as well as in hard copy.

B. Forward and reverse logistics

2.133. e type of census materials would diﬀer depending on census methodologies and

technologies used for enumeration and data processing. However, any kind of materials

related to ﬁeldwork has to be supplied to the ﬁeld staﬀ and returned. Strategies for distribu

tion and return of materials should be carefully planned according to the type of materials,

volume and ﬁnal destination of delivery.

2.134. As a ﬁrst stage in this process, decisions must be made concerning the nature and

responsibilities of the centrally controlled distribution and return operation. For example, a

decision should be made about what geographic levels the materials will be distributed to—

regional oﬃce, local census committee, supervisors or other. ese decisions must be made

by countries, keeping in mind the impact of the amounts of material to be transported, the

transport available to ﬁeld staﬀ and the condition or existence of roads or other means of

transport. Once these decisions have been made, the key inputs to the dispatch and return

of materials are as follows:

(a) Workload estimates from the mapping programme to establish packing volumes

for transport requirements;

(b) Name and address details for delivery and pickup points.

2.135. During the design of enumeration areas and mapping activities, an estimate will be

made of the number of enumeration areas, and the amount of work in each. is information

can be used to calculate how much material will be needed by each enumerator, supervisor,

manager and so on. is method should provide a more accurate estimate of the total volume

of all the materials.

2.136. e majority of these tasks are usually carried out under contract by a government

transport service or commercial operator. e contractor will use speciﬁcations and consign

ment details provided by the national statistical oﬃces. If the volume is small, the postal

service may be a feasible method.

2 .137. A signiﬁcant task in planning ﬁeld operations is establishing the speciﬁcations for the

packing and transport of materials. ese speciﬁcations need to be developed regardless of

whether these activities are carried out by the census agency itself or contracted out to another

government agency or private company.

2.138. e role of the national statistical authority with regard to dispatch and return tasks

is primarily one of liaison and monitoring. For the most part, the contractor will contact

regional managers and supervisors directly about the delivery or pickup of material. e

national statistical authority can expect to be involved as a liaison between the contractor

and ﬁeld staﬀ in the early stages of the operation or if there are any particular problems expe

rienced by either ﬁeld staﬀ or the contractor. e national statistical authority management

staﬀ should meet frequently with the contractor to discuss the operation and liaison arrange

ments. Part of the planning of the operation will include arrangements to enable the national

statistical authority’s management staﬀ to monitor the delivery and return of materials. In

particular, when material is picked up from supervisors, the national statistical authority’s

management staﬀ should maintain a close watch over what is taking place in the ﬁeld as the

transport of completed census forms is involved.

59Planning, organizing and management 59

2.139. Distribution and collection of census materials can be monitored through use of a

management information system (see paragraphs 3.145-3.146). Timely information can be

produced about the progress in delivering census materials and questionnaires and collecting

completed questionnaires and the other return materials. Depending on the logistics pro

gramme, the information needed for monitoring the logistics activities will diﬀer. In general,

the following information would be needed for both forward and reverse delivery: (a) type of

materials, (b) timing of delivery, (c) number of delivered materials, and (d) name of the per

sons involved in the delivery. e periodic reports produced from the management informa-

tion system will be crucial to ensure the timeliness of ﬁeldwork across the country by giving

an alert if there is any delay or any other problems regarding the delivery of census materials.

XII. Contracting out

2.140. It is a contemporary practice in many countries to contract out tasks or activities of

the population and housing census as a way of increasing eﬃciency by utilizing the advanced

methods and technologies not necessarily available in the national statistical oﬃce or public

sector responsible for conducting the census. At the same time, reduction can be achieved

through a competitive selection process. However, not all census tasks are appropriate for

outsourcing or contracting out, and doing so will not necessarily bring the desired beneﬁt

of strengthening national capacities. Census activities may be broadly classiﬁed as core and

non-core activities. As a general rule of thumb, core activities should not be contracted out. If

for some reason core activities need to be contracted out, then it is essential that the strategic

control of such activities should ﬁrmly be with the census authorities at all times.

2.141. In the context of contracting out components of census operations, the national statis

tical authority would need to build the capacity to ensure proper outsourcing. is is of pri-

mary importance at the preparatory stages, as outsourcing requires a solid and comprehensive

knowledge of contemporary technologies and their advantages and disadvantages, as well as

past experiences at home or in other countries. Consequently, the national statistical authority

would need to plan and develop a particular unit for the purpose of ensuring adequate and

eﬃcient outsourcing well in advance of the census itself, as there would need to be extensive

testing of the products and services that were contracted out.

2.142. e terms of engagement (scope of work), the deliverables and the timelines should be

clearly laid down with deﬁnite dispute redresser mechanisms. Illustrative examples of items

of work that can be contracted out are as follows:

(a) Layout and printing of census questionnaires;

(b) Packaging of census questionnaires;

(d) Census mapping;

(e) Publicity and public relations;

(f ) Training;

(g) Return collection of census questionnaires and other material;

(h) Inventory and storage of ﬁlled-in questionnaires;

(i) Scanning and data entry;

(j) Data processing and tabulation;

(k) Publication and dissemination.

Principles and Recommendations for Population and Housing Censuses, Revision 360

2.143. Time is of the essence in all these activities, and it is vital that adequate time is allo-

cated. At the same time, backup plans should be in place in order to deal with any failure on

the part of the vendors. Fundamentally, census operations are time-critical and commercial

compensation is secondary. Depending on whether an activity is on the critical path or not,

adequate ﬂags should be provided. Milestones and timelines are also essential. e moment

there is a failure in achieving any milestone, alerts should automatically be raised. Risk

assessment represents a critical component for outsourcing; the risk of failure, and the costs

involved in developing contingencies in case of failure, require particular consideration.

2.144. e appropriateness of contracting out should be determined step by step and after

subdividing the overall census tasks into stages. In the context of quality management, the

outsourcing of components of census operations still requires the national statistical oﬃce to

take full responsibility for, and manage the quality of, the census data. roughout the overall

process, activities should be conducted by a method (considering accuracy and timeliness of

the results) that can best satisfy the general public. No part of the work should be done by a

method that may result in loss of trust of the general public. When outsourcing, the statistical

oﬃce needs to ensure that it continues to be in a position to understand and manage elements

that contribute to ﬁnal data quality. So, in judging the propriety of contracting out, it is

recommended that national statistical oﬃces should carefully consider the following criteria:

(a) Strict protection of data conﬁdentiality;

(b) Method of conﬁdentiality assurance that satisﬁes the general public;

(d) Ability to manage and monitor the outsourced census tasks or activities;

(e) Control over the core competence of the national statistical oﬃce, and appropri

ateness of judgement, considering the speciﬁc situation of each country.

2.145. Conﬁdentiality assurance is the ﬁrst and most important issue that should be consid

ered by national statistical oﬃces. National statistical oﬃces are responsible for data conﬁden-

tiality, in terms of both perception and reality. It is extremely problematic for national statisti-

cal oﬃces to ﬁnd leakage or misuse of conﬁdential information by ex post facto monitoring

and controls. Consequently, contracting out of tasks that have the risk of such an incidence

should be avoided. For example, in the phase of data gathering, it is highly recommended that

contracting out should be avoided because the task is closely related to the earning of trust

from citizens and the strict protection of conﬁdentiality. Where temporary enumeration staﬀ

are engaged under contract, this should be done in such a way that they are subject to strict

measures of monitoring and control by the national statistical oﬃce. ese enumeration staﬀ

should be engaged in such a way that their activities are governed by the relevant statistical

legislation to preserve the conﬁdentiality of the data they collect.

2.146. e second important and related issue that should be considered carefully is con

veying conﬁdentiality assurance to the general public. As described in the “Essential roles of

the census” (see paragraphs 1.1-1.3), a census should be undertaken by the method that can

produce the most reliable results and in a manner that ensures the trust of the general public

in terms of both perception and reality. If either one of these attributes is not met, then the

method used as well as the results obtained may not meet the approval of the general public

and could result in the census itself being questioned. us, protecting data conﬁdentiality

refers not just to the actual protection of conﬁdential data, but also to protecting the percep

tion of conﬁdentiality among the general public and providing a sense of inward security.

2 .147. e third signiﬁcant issue to be considered in outsourcing is the guarantee of quality

assurance in the outsourcing environment. e key point is that the national statistical oﬃce

is satisﬁed that the goods or services paid for are provided. Cost should not be the ﬁrst priority

in considering and judging the successful bidder in this respect unless prescribed by procure

61Planning, organizing and management 61

ment rules. Although it is desirable to engage in fair competition among several companies

to reduce costs, it is worth mentioning that merely considering low-price bidding as a deter

minant factor may adversely aﬀect the quality of the job to be done by the successful bidder.

Low-quality work could cause a signiﬁcant loss of trust among the general public. To assess

the quality of work, as part of the contract allocation process, potential contractors should be

required to provide samples of their work (for example, for printing, manufacturing satchels,

and other work), or if this is not possible, to list referees who could be contacted to verify their

claims, or sites at which previous work can be inspected. e contracting process should state

all the key requirements for the services sought and bidders should be measured against these.

Although not a guarantee of quality, it will minimize surprises. Once the contract has been

awarded, continuous monitoring of the progress of work entrusted to the selected company

is necessary and the national statistical oﬃce should ensure that a system for monitoring

quality is built into the contract. Consequently, in considering the proper contracting-out

procedures, national statistical oﬃces should also take into account the costs for constructing

a system of surveillance for monitoring progress of the work being contracted out.

2.148. In addition to monitoring the providers of goods and services, national statistical

oﬃces need to plan for continuous interface with the providers. is implies an additional

step to monitoring and amounts to a necessity to work side by side on a regular basis in order

to ensure the best quality of the products and services and to meet the standards and needs of

the census operations. is coordinated work refers to providing technical and technological

advice, as well as following the development of the services and applications from the sub

stantive point of view. While the national statistical oﬃce may not have the full capability to

develop certain products or applications, it certainly possesses considerable technical experi

ence and understanding of producing statistics on a regular basis. erefore, planning for and

implementing a regular and continuous interface with providers when parts of the operations

are outsourced needs to be incorporated in the overall planning from the beginning.

2.149. e fourth major issue in outsourcing census activities is the procedure of assessment

and evaluation of the capabilities of the candidate providers. A quality assurance framework

(for a detailed discussion on quality assurance, see paragraphs 2.169-2.228) and implementa

tion should be established in a ﬁrst phase of outsourcing. rough this procedure national

statistical oﬃces should fully assess both the capabilities and the disabilities of companies in

order to select the winner to which the activities in question are to be outsourced. It is highly

recommended that practical and ﬁnancial peculiarities of providers should be considered after

the assessment of their capabilities. Each private company has a potential risk of bankruptcy

or of changing the ﬁeld of its activity. It should be kept in mind that if a selected company is

unable to fulﬁl the assigned tasks, the probable problems might not be resolved by applying

penalties. However, a very signiﬁcant problem that could occur is that users might not be able

to make use of accurate and timely census results. In such a case, national statistical oﬃces

might lose the trust of the general public in the census and even in future censuses or other

routine statistical projects conducted by the statistical oﬃce. It is, therefore, very important

for national statistical oﬃces to adopt a method in which risks are as low as possible.

2.150. Some approaches to outsourcing put an emphasis on a “turnkey” arrangement, by

which contractors deliver the system according to a set of predetermined client speciﬁcations

with the expectation that the client focuses solely on the outputs and not the internal working

of the system. is assumes that the national statistical oﬃce completely understands and

can fully anticipate all data quality issues that might arise during the census and has included

these in the speciﬁcations. e client is not expected to have any understanding of how these

systems work or how they might contribute to the ﬁnal outputs. Any changes to the system

typically require cumbersome processes to determine contractual responsibilities and heavy

ﬁnancial costs. is sort of approach eﬀectively hands over the quality of the census data to

Principles and Recommendations for Population and Housing Censuses, Revision 362

the contractor, while the risks associated with intervention remain with the census agency. It

removes any ﬂexibility and greatly restricts the ability of the census agency to react to quality

problems that emerge during processing.

2.151. Suppliers should be made fully aware of the quality targets at the outset of the census

programme, and the quality requirements of the outsourced components that enable the

overall census quality target to be achieved. Operational quality control should apply to

outsourced services in the same way as those that are not outsourced.

2.152. In addition to managing the outsourced activities or tasks, the ability or the ﬂexibility

to cope with sudden or unpredicted change in the situation is also very important. It should

be mentioned that contracting out does not necessarily mean lower costs; sometimes the

burden of monitoring cost, emergency costs and other matters may jeopardize the census. It is

recommended that the national statistical oﬃces themselves should do some tasks or activities

that are hard to manage. National statistical oﬃces should judge and determine whether to

contract out census activities from this viewpoint.

2.153. It should also be recommended that for critical activities, such as the coding of educa

tion, occupation and industrial classiﬁcation, special care should be taken to ensure adequate

training of the personnel to undertake the task, particularly when it is contracted out. e

same amount of care and training is required even when the task is performed by the national

statistical oﬃce. is is due to the fact that the coding depends on the minor diﬀerentia

tion and level of coding (general and detailed classiﬁcations according to diﬀerent coding

standards), as well as the coding manual and the education of the coders. In the light of such

subtle criteria for judgement, it is diﬃcult to prepare a complete coding manual in advance

before checking the ﬁlled questionnaire.

2.154. Censuses are large operations with massive quantities of data that require coding and

editing. To reduce the staﬀ resources required and to improve timeliness, uniformity and

accuracy, automated coding procedures may be employed. Some countries have already imple

mented automated coding procedures for addresses, countries, education, occupation and

industry. e development of the application software could be contracted out, although the

rules to be followed must be carefully speciﬁed by the national statistical oﬃce, which should

retain responsibility for implementing the system. e software application can often be used

for other statistical collections undertaken by the national statistical oﬃce. When outsourc

ing, the staﬀ of the national statistical oﬃce should be able to modify the parameters of such

operations themselves at little cost and in a timely manner. By having this ability, the national

statistical oﬃce can manage the appropriate balance between data quality, cost and timeliness.

XIII. Use of technology

2.155. Technological developments and subsequent access to modern technology has largely

eased the way in which the business of a population census is undertaken. Modern technol

ogy permits end-to-end embedding of processes in the census value chain. is possibility

ranges from planning, monitoring and implementation to evaluating outcomes. Many facets

of census activities can beneﬁt from the use of technology. Remote sensing and imaging

technology can now generate live maps with coordinates against which enumeration activi

ties can be tracked. Fieldworkers can be paid their salaries and stipends using mobile device

technology. Handheld devices with inbuilt edit functions and geopositioning capabilities can

improve the consistency of responses while tracking geo-activities, including those that can

report on spatial coverage. Given how pervasive technology can be, it would be imperative to

63Planning, organizing and management 63

select carefully at the planning stage what technological innovation elements will be adopted

in the census value chain.

2.156. Rapid innovation has led to both exponential growth and reduction in costs of tech

nology. ese changes have seen an increased adoption of technology across many aspects of

the census in a variety of diﬀerent ways. While on the one hand this is providing considerable

beneﬁt, on the other it is increasing dependence on technology providers and introducing

new challenges and risks. e key to the successful use of technology in a census is to clearly

understand the rationale or the objective of the technology introduction, and consider a range

of key success factors for technology adoption, which may include suitability, security, scal

ability, stability, safety and skills.

2 .157. e understanding of the value of technology is critical to forming a business case

and assessing whether or not to proceed with the project, and if so what technology choices

to make. As the introduction of technology can be an expensive and risky exercise, it is

important to ensure that there is suﬃcient value in its introduction for each speciﬁc census.

2.158. e most common reasons for the introduction of technology in censuses opera

tions are:

• Eﬃciency and reduction of costs. Technology provides an opportunity to reduce

the number of personnel involved in diﬀerent aspects of the census—for example,

scanning and character recognition can reduce manual data entry and increase

data accuracy, satellite imagery can reduce manual mapping and Internet self-

response can reduce ﬁeldwork. Technology can also reduce other non-labour

expenses such as printing, freight and travel. In some cases, technology can sim

plify business processes and thus reduce cost or risk.

• Data quality and consistency. Technology, and in particular the automation of

processes, can increase the consistency of census data and reduce data errors—

for example, scanning and character recognition reduces data entry errors, and

automated validation rules or edits ensure that data are checked and changed in

consistent ways rather than relying on manual, dispersed ﬁeld processes.

• Timeliness. Technology can reduce the time needed to conduct census enumera

tion, data processing, data analysis and preparation of results for publishing. e

faster the census data are released, the more valuable the data are to census users,

and thus the use of technology for data scanning, recognition, processing and

publishing should be considered for its ability to advance publish dates.

• Public and user expectations. e census relies on the general public to provide

data. e census needs data users to access and utilize census statistics in order

for them to have value. Public and user expectations, and sometimes legal rights,

may make it advisable or necessary to implement speciﬁc technologies to support

these users. ese interactions may be in the form of completing a census ques

tionnaire, applying for census jobs online or receiving census results online. ere

is some evidence that the provision of online questionnaires has had a positive

impact on census response rates.

• Event management. e coordination and monitoring of census enumeration

across the complete nation or area has always been challenging and has relied on

dispersed accountability and manual processes. Technology may be implemented

to provide better visibility, oversight and capacity to monitor performance indica

tors and respond to enumeration events.

• Data retention and utility. e costs of conducting census enumeration are sig

niﬁcant, and thus attempts should be made to optimize the value achieved from

Principles and Recommendations for Population and Housing Censuses, Revision 364

the census results. e use of technology enables census data to be safely managed,

secured and retained, as well as opening up opportunities for statistical data inte

gration and data reuse, such as for time series analyses and other analytical needs.

• Assurance and anticorruption. e adoption of technology can reduce the risk of

fraud or corruption through providing more standardized, controlled and audit

able records of actions, for example for the records of ﬁnancial expenditure.

2.159. When considering the reasons listed above in a business case for a technology project,

it is likely to become clear that there is some tension between these reasons, and there will be

some trade-oﬀs that should be considered openly and transparently. For example, a solution

that attempts to meet more user expectations may ultimately cost more and thus while being

positive from this perspective would be negative in relation to programme eﬃciency.

2.160. While the conduct of signiﬁcant technology projects is becoming increasingly com

monplace across government, there is limited evidence to suggest that mere technology

introduction would deliver the projects on time and within budget. Careful planning and

management is critical to the success of these projects. e unique size, timing and nature of

a census throw up unique challenges, which need careful consideration. e following fac

tors should be taken into consideration in the context of optimizing the use of contemporary

technology for census operations:

• Suitability. e functions and beneﬁts of any new technology need to be assessed

thoroughly and objectively against speciﬁc national needs, priorities, laws and

capability to ensure that the potential of the technology can be translated into

value for the census. Consideration of whether the technology has adequate user-

friendliness for the intended user is another important point.

• Scalability. It is pertinent to consider at the outset whether, given the enormous

scale of the census, it is even possible for the solution to handle the load, not just

how to implement the solution. If the technology solution is not designed, imple

mented and tested to be able to handle the number of users, the number of data or

the volume of paper that is required, then it is likely to slow down, stop or cause

errors. is can have a disastrous and unrecoverable impact on the census overall,

as well as on the reputation of the national statistics authority conducting the

census. Hardware and software used in delivering technology must be scalable to

the actual load of each business process during the census project.

• Security. e security of census data is critical for guaranteeing the conﬁdential

ity of respondents’ personal information. e use of technology creates an envi-

ronment that can facilitate the disclosure of individual information compared to

the use of paper questionnaires if appropriate security measures are not put in

place. e use of technology also creates opportunities for an increased number

and location of potential attackers trying to access census data or disrupt the

census programme. Census systems, especially an online census, must be secured

to protect privacy of respondent data and to ensure respondent conﬁdence in

the system. Systems need to preserve conﬁdentiality, integrity and availability of

census information.

• Stability. A census relies on the successful conduct of enumeration in a tightly

time-bound period. As the reliance on technology increases, it introduces the

potential for one central failure having an impact across the whole enumeration

process, with disastrous results. In contrast, in a more manual, traditional cen

sus, failures are more likely to have localized impacts. e failure of a key piece

of technology—such as the census call centre, self-response portal or self-help

65Planning, organizing and management 65

website—close to census day may have an unrecoverable impact on data response

rates, particularly in countries using self-response.

• Safety. e introduction of technology, whether it be paper cutters (“guillotines”)

to assist with the form preparation for scanning or handheld devices for ﬁeld

oﬃcers, introduces safety risks for employees that need to be assessed alongside

the technology and during the technology’s implementation.

• Skill. e census organization, whether planning to outsource or deliver the solu

tion internally, must ensure that it has the adequate skill, knowledge and capacity

to lead and manage this project.

2.161. Census technology projects require strong project management expertise and thus

adequately competent, experienced, motivated and knowledgeable staﬀ need to be assigned

to this role.

2.162. Detailed business requirements (what the technology needs to do and how it needs to

do it) need to be developed by a suitably skilled business analyst in order to ensure that the

technical speciﬁcations and implementation are aligned to the needs of the census.

2.163. Testing is essential for the statistical or census oﬃce to know the various stages that

are aﬀected by the new technology. Separate tests should be conducted to prove new technol-

ogies and identify potential problems linked to implementation. Depending on the extent and

characteristics of information technology, these tests should include all information technol

ogy components related to ﬁeldwork, data transfer or entry and processing well ahead of the

census itself. Tests should include the application systems and the equipment, as well as the

underlying circumstances necessary to avoid equipment malfunctioning.

2.164. A pilot census ensures that technology can be tested as part of a complete, end-to-

end business process and highlights major implementation challenges with functionality or

capability. However, the pilot census alone is insuﬃcient to fully test technology due to its

reduced size, reduced public proﬁle and non-existence of some risks that are present in a fully

ﬂedged census operation. e pilot test should be accompanied by activities to test whether

technology solutions are scalable, secure, accessible and robust enough for the real census.

Stress tests should be conducted during the testing phase to ensure technology use can handle

the maximum load of each module or business case and sustain data integrity.

2.165. ere is an increasing adoption of technology in every national statistical oﬃce across

the world. A number of nations have been developing their own technology solutions to

support diﬀerent aspects of the census, with some of these products being made available

for statistical organizations in other countries. When making decisions around technology

selection or development approaches, there should be strong, favourable consideration of

existing products within the international census community, and where products do not

already exist, the preference should be to undertake co-development with other members of

the statistics community.

2.166. ere are a number of risks or drawbacks associated with the introduction of technol

ogy that should be considered and managed, otherwise these could lead to increases in expend-

iture, delays to the census timetable or impacts on the quality of the census. ese include:

• Incompatibility or other integration issues between diﬀerent hardware and soft

ware applications;

• Solution outage or failure (which could be for many reasons—lack of connectiv

ity, hardware failure, battery life, GPS black spots, software bugs, device theft);

• Lack of skills or knowledge by system users, particularly temporary census staﬀ;

Principles and Recommendations for Population and Housing Censuses, Revision 366

• Insuﬃcient or inadequate communication between technology staﬀ and business

staﬀ, particularly leading to misunderstanding of requirements;

• Hacking, online attack or other information technology security event;

• Maintaining, upgrading or decommissioning old or legacy systems;

• Lack of documentation or reliance on a small number of key people;

• Huge amount of digital data available, creating a potential distraction for staﬀ.

2 .167. A wide range of technologies, covering all stages of the census from planning to

data dissemination, is presented throughout all the chapters of these principles and recom

mendations. However, the integration of technologies in census operation requires taking

into account various speciﬁc national needs and the value each technology would bring to a

speciﬁc aspect of the census.

2.168. e utilization of technology is expected to vary considerably in statistical oﬃces

across the world, considering the need and the resources that are available to the national

statistical system. Ultimately, technology is an enabler that can enhance eﬃciency, accuracy,

speed and transparency of census operations. It can also lead to optimization of costs, depend

ing on the circumstances of each nation. It is to be reiterated, however, that the choice of

technology and its level of deployment should be diligently assessed by each country before

introduction.

XIV. Quality assurance

A. Plans for quality assurance

2.169. Most countries conduct population and housing censuses once in 10 years, so carrying

over experience from one census to the next is fairly limited. But experience from previous

population and housing censuses as well as other censuses, such as agricultural censuses, is

very useful to plan for a quality assurance and improvement programme for the current cen

sus. Moreover, numerous activities that comprise the census operation have to be carried out

in a limited time period. is means that countries must employ a large number of persons

for census work for a few weeks or months. Usually a diﬀerent set of persons are employed

on a temporary basis for each of these operations. As a result, the quality of work is likely to

vary from person to person, from one area to another and from one time to another. It would

be very useful—indeed of critical importance—if errors detected from previous censuses or

similar activities were documented and used as the basis for developing quality assurance

measures for the next census. Each country must have a quality assurance and improvement

programme in place to measure the quality of each stage of the census. It is therefore impor

tant to be able to measure how well each census operation is proceeding by building in quality

assurance procedures throughout the census. It should be stressed that a major goal of any

quality assurance programme is to detect errors so that remedial actions can be taken even as

the census operations continue. us, a quality assurance programme should also be viewed

as a quality improvement programme. Without such a programme, the census data when

ﬁnally produced may contain many errors, which can severely diminish the usefulness of the

results. If data are of poor quality, decisions based on these data can lead to costly mistakes.

Eventually the credibility of the entire census may be called into question.

2.170. e quality assurance and improvement system should be developed as part of the

overall census programme and integrated with other census plans, schedules and procedures.

e system should be established at all phases of census operations, including planning, pre-

enumeration, enumeration, document ﬂow, coding, data capture, editing, tabulation and

67Planning, organizing and management 67

data dissemination. Following a detailed schedule will ensure that suﬃcient time is allocated

to testing and evaluation activities at each stage, reducing the risks of errors. Establishing a

quality assurance and improvement system at the planning stage is crucial to the success of

the overall census operation.

B. Quality assurance components

2.171. Quality management should be comprehensive and should cover all activities includ-

ing planning, development, data collection, processing, evaluation and dissemination of

results. e consequences of census data being of poor quality may be detrimental to policy

decisions; more importantly and ultimately, the credibility of the entire census, the compe

tency of the national statistical system and the government itself will be put into question

and the trust of society may never be fully recovered.

2.172. ere is general agreement that, in the end, quality has to do with user needs and sat

isfaction. In statistics, quality used to be primarily associated with accuracy; in other words,

taking mainly into account errors, both sampling and non-sampling, that inﬂuence the value

of the estimates, and intervals based on such knowledge upon which precise conﬁdence state

ments could be made. Such measures are still considered necessary, but it is recognized that

there are other important dimensions to quality. Even if data are accurate, they do not have

suﬃcient quality if they are produced too late to be useful, or cannot be easily accessed, or

conﬂict with other credible data, or are too costly to produce. erefore, quality is increas

ingly approached as a multidimensional concept.

2.173. Quality is the outcome of processes, and deﬁciencies in quality (for example, delays

in processing or lack of accuracy in the results) are usually the result of deﬁciencies in process

rather than the actions of individuals working in that process. erefore, processes should

at least show:

(a) Methodological soundness and adherence to professional methods and (internation

ally) agreed standards;

(b) Eﬃciency, the degree to which statistics are compiled in such a way that the cost

and the respondent burden are minimized relative to output.

2.174. Quality will be better supported by sound institutional arrangements, such as:

(a) Legal environment, the degree to which statistical legislation is enacted in con

formity with the Fundamental Principles of Oﬃcial Statistics;

(b) Planning mechanisms, the degree to which countries have instituted procedures

for systematic, long-term planning of statistical operations;

taken in relation to (diﬀerent types of) cost and to each other;

administrative authority.

2.175. It is suggested that the output of any statistical exercise should possess some or all of

the following attributes:

(a) Relevance, understood as the degree to which statistics meet user needs, and sug

gesting the need to avoid production of irrelevant data, namely data for which

no use will be found;

(b) Completeness, the degree to which statistics fully cover the phenomenon they are

supposed to describe;

Principles and Recommendations for Population and Housing Censuses, Revision 368

(d) Comparability, the degree to which statistics are comparable over space (between

countries) and time (between diﬀerent time periods);

(e) Coherence, the degree to which data from a single statistical programme, and data

brought together across statistical programmes, are logically connected;

(f ) Timeliness, the time elapsed between release of data and reference period;

(g) Punctuality, the degree to which preannounced release dates are met;

(h) Clarity, the degree to which statistics are understandable for non-expert users;

(i) Accessibility, the ease with which statistical data can be obtained by users;

(j) Interpretability of census data, including metadata, availability of information

describing sources, deﬁnitions and methods;

(k) Trust, in terms of the public’s trust in the national statistical authority and its

deliveries.

2.176. In the census context, some attributes of quality assurance may be emphasized over

the rest. e census should produce statistics that are relevant to data users. A census is a

particularly expensive exercise to undertake and creates a burden on respondents. erefore,

it is crucial to ensure that any demand for data is met to a minimum and that topics for

which there is little demand are not included on the census form. Consulting with users

of census data as one of the ﬁrst steps in designing the census process is a positive public

relations undertaking and an eﬃcient, transparent means of determining the demand for

potential census topics.

2 .177. e relevance of data or of statistical information is a qualitative assessment of the

value contributed by these data. Value is characterized by the degree to which the data or

information serve to address the purposes for which they are produced and sought by users.

Value is further characterized by the merit of those purposes, in terms of the mandate of the

agency, legislated requirements and the opportunity cost to produce the data or information.

In the context of a census the concept of ﬁtness for purpose as a measure of relevance is impor

tant. If it is only necessary that data are available at the broad level (for example, national or

major civil division level of geography; broad demographic level), user requirements could be

met more cheaply and eﬀectively through a sample survey.

2.178. Completeness is an extension of relevance, for completeness means not only that sta

tistics should serve user needs, but also that they should serve them as completely as possible,

taking restricted resources and respondent burden into account.

2.179. Accuracy of data or statistical information is the degree to which those data correctly

estimate or describe the quantities or characteristics that the statistical activity was designed

to measure. Accuracy has many attributes, and in practical terms there is no single aggregate

or overall measure of it. Of necessity these attributes are typically measured or described in

terms of the error, or the potential signiﬁcance of error, introduced through individual major

sources of error, for example coverage, sampling, non-response, response, processing and

dissemination.

2.180. Data are most useful when they enable reliable comparisons across space, such as

between countries or between regions within a country, and over time. More and more

emphasis is also put on enabling comparison of geography over time, as well as maintaining

consistency and comparison of census topics from one census to another.

2.181. Timeliness of information reﬂects the length of time between its availability and the

event or phenomenon it describes, but considered in the context of the time period that per

69Planning, organizing and management 69

mits the information to be of value and still acted upon. It is typically involved in a trade-oﬀ

with accuracy.

2.182. Accessibility reﬂects the availability of information from the holdings of the agency,

also taking into account the suitability of the form in which the information is available, the

media of dissemination, the availability of metadata, and whether the user has reasonable

opportunity to know they are available and how to access that information. e aﬀord

ability of that information to users in relation to its value to them is also an aspect of this

characteristic.

2.183. Data coherence reﬂects the degree to which the census data can be combined with

other statistical information within an integrated framework over time. e use of standard

concepts, deﬁnitions and classiﬁcations promotes coherence. Equally important is internal

coherence of data, referring to the consistency of information across diﬀerent topics of the

census and census outputs. is coherence is usually addressed through the meticulous devel

opment of data edits.

2.184. e cost of providing information, respondent burden and ability of the respondent to

provide the requested information are also components of the trade-oﬀ with accuracy and time

liness. If this were not so, data could achieve (near) perfect accuracy with little or no time delay.

C. Need for a quality management system

for the census process

2.185. e essential quality attribute of relevance of census output, and how to assure it, has

been discussed above together with the need for consideration of accuracy, timeliness and

cost. Quality is relative, and in the end is based on what is acceptable or ﬁt for the purpose,

rather than a concept of absolute perfection.

2.186. Deﬁciencies in quality (for example, delays in disseminating output) are usually the

result of deﬁciencies in process rather than the actions of individuals working in that process.

e key to quality assurance and improvement is to be able to regularly measure the cost,

timeliness and accuracy of a given process so that the process can be improved when a decline

in quality is indicated. e focus of quality assurance is to prevent errors from reoccurring, to

detect errors easily and early, and to inform the workers so that they do not continue making

them. is simple feedback loop is represented in ﬁgure 1.

Figure 1.

Quality assurance circle

This section draws heavily upon

material in Handbook on Census

Management for Population and

Housing Censuses, Studies in

Methods No. 83 (United Nations

publication, Sales No. 00.XVII/

Rev.1), chapter 1C.

Measure quality

Identify most

important quality

problem

Identify root

causes of problem

Implement

corrective action

Principles and Recommendations for Population and Housing Censuses, Revision 370

2.187. Being iterative, the quality assurance circle is particularly applicable to tasks that are

highly repetitive, such as the processing phase of the census. However, the general principle

applies to all processes. For example, there is less opportunity to evaluate performance, iden

tify problems and implement corrective actions in phases such as enumeration owing to time

constraints, and the once-only nature of some of the processes and communication issues.

However, it still can be established with careful planning and documentation in advance of

the census.

2.188. It is important that a complete evaluation takes place and is documented at the end

of each phase of the census. is should be done particularly for phases such as enumera

tion, so that the organizational learning inherent in the quality circle is carried forward to

the next census.

2.189. Since people play a key role in most census processes, they are in a good position to

identify problems with quality and provide solutions. Quality is therefore not just the out

come of mechanical application of predetermined measures but relies on a combination of:

(a) Established, documented processes, including quality targets (for example

response rates, level of error in processing);

(b) Systems to monitor the outcomes of these processes;

in identifying and resolving deﬁciencies with quality.

2.190. While elements of the quality circle, such as mechanisms to monitor quality, may

have some superﬁcial resemblance to some of the elements of traditional quality control

approaches, they are quite diﬀerent.

Traditional quality control is based on correction of

error after the event, whereas the emphasis of the quality circle is on improving the process

that caused the “error”, which may be any of the cost, timeliness or accuracy attributes falling

below speciﬁed levels. A simple error correction process may suﬀer from any of the following:

(a) It adds signiﬁcantly to the cost of the operation;

(b) Errors in the inspection process can fail to detect true errors or falsely identify

errors;

(d) Operators take less responsibility for the quality of their work, believing it to be

the responsibility of the inspectors;

(e) Where a sample of units is inspected, the quality of data is only ensured for those

units that are inspected.

2.191. e emphasis should be on process improvement rather than correction. erefore,

an important aspect of quality management may be to not correct errors detected through

the quality monitoring process unless they are of a severe nature or are generally applicable.

For example, a generally applicable error could be a systems error that miscodes every occur

rence of a common event. Resources are thus better focused on improving processes and thus

overall quality.

D. The role of managers

2.192. Managers have a vital role in establishing quality. e biggest challenge to managers

is ﬁrst to establish a culture within the census agency that has a focus on quality issues and

to obtain the commitment of staﬀ to strive to achieve high-quality goals. At the same time,

managers need to be aware that to achieve high-quality outcomes they need to give their staﬀ

Handbook on Census Manage-

ment for Population and Housing

Censuses, contains in annex IV a

case study of a system combin-

ing the quantitative components

of the traditional system within

a conceptual framework of a

quality management approach.

Annex IV also illustrates the

important diﬀerences between

the two approaches.

71Planning, organizing and management 71

responsibility to achieve these outcomes. Managers who do not delegate responsibility will

ﬁnd it diﬃcult, if not impossible, to establish teams that strive for high-quality outcomes.

2.193. e project manager is responsible for project work from the initial kick-oﬀ through to

closure. Only the primary responsibilities are given in the list below, and so it can be expanded

considerably. e responsibilities of the project manager include:

(a) Using quality project management tools and techniques;

(b) Identifying and managing the project stakeholders;

i. Setting team norms and behaviours within the team;

ii. Deciding responsibilities and coaching team members in new skills;

iii. Leading, guiding and directing team members;

iv. Controlling the work of the team—input and output;

v. Building trust and respect in the team;

vi. Encouraging personal growth, development, empowerment and continuous

learning of the team members;

(d) Establishing a project support oﬃce:

i. Developing project plans and budgets aligned to established strategy;

ii. Prioritizing activities within the project;

iii. Allocating and securing resource (for example ﬁnancial and technological)

commitments;

iv. Working with established working practices and customs, and developing

relevant policies, systems and processes to implement objectives and plans;

v. Developing a project communication plan;

vi. Developing a governance framework for the project;

vii. Monitoring and tracking project progress against set objectives and plans,

and compiling relevant reports, for example progress, variance and status

reports;

viii. Monitoring and controlling expenditure and compiling ﬁnancial and vari

ance reports;

ix. Solving problems that interfere with progress;

x. Informing stakeholders of progress and status;

(e) Identifying and managing project risks;

(f ) Working with the unknown and unpredictable;

(g) Implementing improvement and change initiatives;

(h) Delivering project deliverables and beneﬁts;

(i) Leading the project team;

(j) Evaluating and closing the project.

2.194. Managers must ensure that staﬀ understand the philosophy behind the approach to

quality. As mentioned above, staﬀ involvement is a vital ingredient to quality improvement.

erefore, an environment needs to be established in which staﬀ contributions are expected.

2.195. e second part of a manager’s role is to ensure that clients’ expectations are known,

and that these expectations are built into planning objectives and into the systems that are

to deliver them.

Principles and Recommendations for Population and Housing Censuses, Revision 372

2.196. ird, processes need to be documented and understood by the staﬀ implementing

them. Systems and processes for implementing the quality circle also need to be documented

and put in place. Questions such as how quality is going to be measured, who is involved

in identifying root causes of problems with quality, and how the process improvements are

going to be implemented need to be answered. ese will vary greatly depending on the

nature of the process. Appropriate quality assurance techniques for each phase of the census

are summarized below.

2 .197. e greatest test of management commitment to genuine quality improvement will

occur in how management approaches problem solving. Staﬀ will monitor management

responses closely and adjust their own behaviour accordingly. Staﬀ will act in accordance

with how they see managers behave rather than what they hear managers say.

2.198. Managers who always react to problems by seeking people to blame, or who establish

systems that focus disproportionately on the merits or demerits of individuals at the expense

of the team, are sending messages that are contrary to the thrust of quality improvement.

An environment where the emphasis is on fault ﬁnding, rather than on ﬁnding solutions to

problems, or on excessive competition, will assure that staﬀ cease to be part of the solution

and become part of the problem. Managers need to take upon themselves the responsibility

for problems, as they are ultimately responsible for the systems or processes that caused the

problems. ey should not seek to transfer the problems to lower-level staﬀ.

2.199. However, even in the best-managed processes, there are circumstances where indi

viduals can be justiﬁably responsible for negatively impacting quality. ese may be individu-

als who do not possess adequate skills for performing their duties, and even deliberately ﬂout

procedures. ese individuals need to be dealt with decisively, ﬁrst and foremost, primarily

by providing additional training and guidance all the way to administering disciplinary

measures. Managers must deal promptly with these cases and act in a consistent manner. By

doing so, managers will demonstrate to all other staﬀ their commitment to quality.

2.200. To be successful, it is necessary to create a culture in which everyone has the oppor

tunity to contribute to quality improvement. Most of the staﬀ engaged in census operational

work undertake routine tasks, and it is up to management to help them see the bigger pic

ture, to motivate them and to encourage them to assume ownership of their work. is can

be done by promoting a commitment to quality improvement and by adopting a consistent

approach to management.

E. Quality improvement and the census

2.201. e quality circle can be applied to the entire census cycle with:

(a) Performance in the previous phase being evaluated at any given level of detail;

(b) Problems with quality ranked in order of importance;

2.202. e dependencies in the census cycle are represented in ﬁgure 2.

2.203. It is worth noting that it is possible to start at any point in the diagram and achieve

the same result.

2.204. e following sections outline the way in which the concept of a quality circle is

superimposed on the census cycle. Much of the discussion on form design, enumeration,

processing and dissemination is in terms of relevance and accuracy. However, these are subject

to constraints of time and cost that may be established prior to commencing the census cycle.

ese are discussed brieﬂy below.

73Planning, organizing and management 73

Figure 2.

Quality circle dependency chart

1. Topic selection

2.205. e ﬁrst step in managing the quality of the product (namely, census statistics to be

produced) is to ensure that the product will be relevant. e key process is extensive consul

tation with actual and potential users of census information. e key success factor in this

process is full, frank and open communication with users and representatives of all areas

concerned with the census (in particular, subject matter and classiﬁcation experts). As should

be expected, users are reluctant to propose their needs for a future census until they have been

able to assess the extent to which their current needs have been satisﬁed by the output from

the previous census. is should be seen as an evaluation process feeding into the current

cycle, the ﬁrst step of quality management.

2. Form design and testing

2.206. e next quality management task concerns the testing of each census question and the

testing of the design of the form (paper or electronic version according to instrument(s) used).

Again, the quality circle approach is used, with the results of each test being analysed and evalu

ated before being fed into further design and testing. e following areas are the key internal

stakeholders of the form design process and their requirements need to be taken into account:

(a) e dissemination team (to ensure that the questions asked will deliver data that

meets the needs of users);

(b) e subject matter specialist team;

positioning of text and delineation of response areas may be dependent on data

Topic selection

Field operations

Dissemination

Form design

and testing

Data processing

Evaluation:

1. Data quality

2. Process

3. Products/services

Classiﬁcation

and subject

matter specialists

Principles and Recommendations for Population and Housing Censuses, Revision 374

capture and the processing methodology to be adopted. It is critical that there is

ongoing coordination between the form design and processing areas;

(d) e ﬁeld operations team, which is responsible for training the enumeration

workforce and printing the form.

3. Field operations

2 . 2 07. e quality management process continues throughout the design of the census ﬁeld

operations. ese are tested as far as possible in conjunction with form designs testing. e key

internal client of ﬁeld operations is processing. However, ﬁeld operations can also impinge on

other areas, such as dissemination and classiﬁcation and subject matter areas where certain con

cepts, such as what constitutes a dwelling, are implemented during the ﬁeld operations phase.

Several components of ﬁeld operations can be subject to speciﬁc quality circle mechanisms as

these are likely to take some time and involve iterative processes. ese components include:

(a) Demarcation of enumeration areas;

(b) Map production;

standards.

2.208. All systems supporting data collection must be thoroughly tested before collection.

is is especially critical if new collection technology is used, such as handheld or laptop

computers. All data quality beneﬁts of using such technology could be compromised if prob

lems arise during enumeration.

2.209. Quality monitoring should be established for each of these components, and mecha

nisms put in place to ensure that the outcomes of the monitoring are used to improve pro-

cesses. It is more diﬃcult to implement the quality circle during actual enumeration owing

to the very tight time constraints. However, this can be achieved by:

(a) Clearly establishing the aims of the ﬁeld operations phase;

(b) Applying thoroughly documented procedures;

ing and providing inspection of corrupted forms;

(d) Providing opportunities for ﬁeld staﬀ to be observed operating on the job so that

feedback can be given and retraining undertaken;

(e) Establishing communication and feedback loops with the general public through

helplines, online forums, social media, etc., so that problems in the ﬁeld can be

detected and corrected in real time.

2.210. However, it has to be acknowledged that during the actual carrying out of the enu

meration, this approach tends to identify “problem enumerators” rather than systemic or

process errors. is means that evaluation following collection is vital. e evaluation should

attempt to capture the experiences and suggestions of a range of enumerators and other ﬁeld

staﬀ so that improvements can be made to the subsequent census.

2.211. A general overview of the quality of enumeration can be obtained through:

(a) Use of techniques such as post-enumeration surveys to gauge the level of under

enumeration or overenumeration of people and dwellings;

(b) Overall response from the target population or level of non-response at the ques

tion level;

(d) Measures of the quality of any coding undertaken by ﬁeld staﬀ;

75Planning, organizing and management 75

(e) Mechanisms that may be in place to handle queries from the public;

(f ) Analysis of administrative data.

2.212. e eﬀectiveness of the public communication strategy may be assessed by the amount

of press coverage (positive and negative) of the census and follow-up surveys to test the reac

tion to particular advertising.

4. Processing

2.213. e key clients of processing are the areas of the statistical agency responsible for

disseminating and maintaining standard classiﬁcations, and those with special subject-matter

knowledge. e dissemination area depends on the processing team to obtain data in an

agreed format and compiled to agreed quality standards. is is necessary so that the data

can be used in dissemination systems.

2.214. Since the census is part of an overall national statistical system, data from the census

are likely to be used in conjunction with data from other collections. us the classiﬁcation

and subject matter specialist areas, which are responsible for those other collections, need to

be satisﬁed that the coding, editing and other data transformation processes are conceptually

sound and deliver data of acceptable quality.

2.215. Extensive testing of processing systems must be undertaken in advance of the census.

Coding processes and training packages need to be prepared and tested using the type of staﬀ

likely to be involved in the operations. e processing phase gives the fullest scope for the use

of quality improvement techniques, as many of the processes in this phase are repetitive and

take a signiﬁcant amount of time. is enables the quality circle to go through much itera

tion. It is vital that structures are put in place not only to monitor quality but also to involve

processing staﬀ in the identiﬁcation of problems with quality and in proposing solutions.

2.216. It is generally not possible for processing to improve the accuracy of census data. At

best, processes such as editing may reduce some inconsistencies within the data. However, in

the end, the data coming from the processing system will not be of any better quality than

the information supplied on census forms. Much eﬀort can be expended in correcting appar

ently inconsistent or inaccurate census data with no real improvement in the ﬁtness for the

purpose of the data. It may be a better strategy to educate users to accept slight inconsistencies

in census data, rather than developing complex procedures that may introduce other errors

and impose heavy costs in terms of delay in release of the data and cost to the community.

5. Dissemination

2 . 217. Census dissemination can easily be overlooked in the chain of providing a quality

outcome for the census as management attention is diverted to the costly and risky enumera

tion and processing operations. e dissemination area is responsible for the timely delivery

of products and services to census data users. erefore, insuﬃcient planning and resources

for this phase can have the eﬀect of delaying the release of the data and thus compromising

the overall achievement of census objectives. e dissemination phase should also be regarded

as an ongoing process that will serve the needs of users over a long period of time.

2.218. Management of quality in census dissemination is driven by concerns to (a) deliver

relevant products and services; (b) maintain accuracy of the data; and (c) ensure timeliness

and predictability of data release within agreed cost constraints.

2.219. e ﬁrst of these objectives is to provide relevant products and services. is can only

be done by reviewing the experiences of the previous census products and services and by user

consultation processes with both current and potential users of census data.

Principles and Recommendations for Population and Housing Censuses, Revision 376

2.220. e second objective is to ensure that the data supplied from the processing system

are accurately transformed into output products. A quality assurance strategy to ensure that

data tabulations and transformations are carried out accurately needs to be documented and

followed. e quality circle approach to these processes needs to be applied and any gaps

identiﬁed and corrected through extensive testing prior to the census and ongoing process

improvement during the dissemination phase.

2.221. e third objective is the timely and predictable release of data from the census. While

this is the responsibility of all phases of the census programme, the role of dissemination is

crucial. e dissemination area needs to be realistic about release dates and ensure that these

are communicated to clients early so as to manage client expectations. e involvement of

staﬀ actually responsible for the dissemination phase in devising these dates is recommended

where this is possible. Dissemination systems and processes need to be available, documented

and tested prior to the release of data from the processing phase.

2.222. A release calendar needs to be prepared to keep the user community informed about

the likely month of release so use of data can be planned in advance. A mechanism to provide

metadata on census indicators and the geography level at which these are made available

needs serious consideration. Every country should assess the requirements and put in place a

dedicated team to assist data users. e services of call centres may be used if the number of

data seekers cannot be handled in-house.

6. Evaluation

2.223. Evaluation of the overall census operation is vital for identifying strengths and weak-

nesses of census phases, including planning, enumeration, data processing and dissemination,

and also for the purpose of analysing the quality of census statistics, which are the major output

of these processes. With the quality assurance and improvement programme, the main objec

tive is to ensure that quality assessment is consistently incorporated in all phases of the popula-

tion and housing census, focusing on eﬀorts in controlling the occurrence of errors and taking

actions to ensure the highest quality of both the processes and their outcomes. Errors appear

to be inevitable in such a complex undertaking—consequently, there needs to be a mechanism

put in place to determine the deﬁciencies and their quantitative impact on census results.

2.224. Census evaluation with all dimensions of quality (see paragraph 2.175) requires a

comprehensive evaluation programme for assessing and documenting the outcomes of each

process using appropriate and customized methodologies. Methodologies for evaluation

should be planned well in advance, in the planning phase of the census. It should be noted

that this is a continuous process implemented from the planning to the end of census opera

tions. It is also appropriate to consider it as being the ﬁrst step in the subsequent census cycle.

Similarly, evaluation of one process within a census cycle could be the ﬁrst stage in the next

process of the same census cycle.

2.225. Evaluation of the accuracy of the census data should also be undertaken, to the extent

possible, by conducting a post-enumeration survey for measuring coverage and content errors,

by comparing the census results with similar data from other sources and by applying demo

graphic analysis. As for other sources, these include surveys and administrative records in

a similar time frame, and previous census results. e purposes of evaluating the accuracy

of the data are to inform users of the quality of the current census data and to assist in

future improvements. Future improvement may be achieved by (a) improving processes and

(b) establishing performance benchmarks against which the quality of the data from subse

quent censuses can be measured.

77Planning, organizing and management 77

2.226. Evaluation of data accuracy may have two parts. Preliminary evaluation will enable

the identiﬁcation of any problem areas that have not been previously detected through the

quality management processes in earlier phases of the census. More extensive evaluation

should be undertaken on data items where problems have been identiﬁed or where new ques

tions or processes have been attempted.

2 . 2 27. e census evaluation programme would be undertaken by subject specialist staﬀ

according to the agreed goals and methodologies covering all possible dimensions of quality.

e following are some examples:

(a) Identiﬁcation of the deﬁciencies and achievements in data capture, coding and

editing (through mechanisms developed for checking the quality of process and

the work of personnel);

(b) Relevance of census data to user needs and satisfaction of users with dissemination

tools and products (based on information collected through user consultation);

identiﬁcation of possible improvements for the next census;

(d) Estimating coverage and content errors of census data (based on demographic

techniques or a post-enumeration survey);

(e) Realization of the census calendar, including the calendar of releasing census

results, and, in the case of changes to the calendar, the reasons and consequences.

2.228. e results of evaluations of census operation for both operational aspects and the

quality of data should be made available to the stakeholders.

Part three

Census operation activities

I. Introduction

3.1. Part three of the Principles and Recommendations focuses on elaboration of census

operations for a traditional census as it is described in part one. While the population and

housing census is in essence a statistical data collection exercise, it still incorporates compo

nents that are not present in a routine statistical survey conducted within the frame of the

national statistical system. In consequence, the layout of this part follows the frame and the

logic of the Generic Statistical Business Process Model;

it also provides particular methodo-

logical and operational guidelines relevant to the population and housing census. is part

of the Principles and Recommendations, therefore, starts with a discussion on developing the

census questionnaire, building census infrastructure, mapping, testing, living quarters and

household listings, ﬁeld enumeration, data processing, evaluation of the results, dissemina

tion, analysis, archiving, documentation and evaluation of overall census operations.

II. Census questionnaires: content and design

3.2. e preparation of the census questionnaire refers to a well-designed process that

should start at a very early stage of the census. is process includes developing various

methods and tools that understand user needs and national priorities. In addition to com

municating with users, other factors that would have impacts on selection of census topics,

such as quality of data collected through the previous census, timeliness, national sensitivity

for speciﬁc topics and available resources, should be taken into account.

3.3. Taking into consideration that the basic principle is to meet user needs and to make

census statistics as useful as possible, the content of the census questionnaire would be deter

mined with the involvement of census data users from diﬀerent sectors, such as governmental

organizations, research institutions, the private sector, the public, civil society and non-gov

ernmental organizations. e consolidation of the results of the consultation with all stake-

holders needs to be balanced by factors such as the response burden, respecting respondents’

privacy and other critical considerations such as costs.

3.4. e ﬁnal content and design of the questionnaire will also be the result of rigorous

and meticulous testing. It is necessary that all aspects of the census questionnaire, such as

wording, structure of the questions and design, be carefully tested

to ensure successful

application of the questionnaire in the ﬁeld.

3.5. Given its multidimensional features, preparation of the census questionnaire requires

most careful consideration, since the handicaps of a poorly designed questionnaire cannot be

overcome during and after enumeration. Successful implementation of this process will have

signiﬁcant impacts on quality of data and census outputs.

United Nations Commission for

Europe on behalf of the Inter-

national Statistical Community,

Generic Statistical Business Process

Model (GSBPM), Version 5 (2013).

For more information about

census tests, see chapter IV.

Principles and Recommendations for Population and Housing Censuses, Revision 380

(a) Selection of census topics

3.6. As a ﬁrst step in determining the content of the census questionnaires, the topics that

will be covered in the census should be selected, taking into consideration the priorities of

national needs, international recommendations,

historical comparisons, international com-

parability, suitability of topics for collecting reliable information and resources available for

the census. Census takers should evaluate national needs in the light of possible new topics

and the needs for continued assessment of the topics covered in the past. e topics that are

not needed in the census because of changing data needs and availability of alternative data

sources should be carefully reviewed in this process.

3.7. During the process of selection of census topics, data users and interested parties

should be consulted for their views on the type and extent of socioeconomic information

they believe the census should provide. e results from consultations should be reviewed

in conjunction with resources available for the census and the burden to respondents. e

length and complexity of the questionnaires should be carefully examined while deciding

what topics will be covered in the census. More information on the factors determining the

selection of census topics is given in chapters I and II of part four.

3.8. Another factor that should be considered in the process of selection of census topics

is related to the decision on whether to use a single census questionnaire for all respondents

or adopt a two-questionnaire approach—short-form and long-form questionnaires. Using a

single questionnaire consists of a standard set of questions for all individuals and housing

units covered in the census. In the latter approach, countries use a short-form questionnaire

with basic questions for enumerating all of the population, while a long-form questionnaire

is applied to a sample of population for collecting more detailed information. Subsequent

paragraphs provide a more in-depth elaboration of this approach.

(b) Use of short and long questionnaires

3.9. With each new census and the advancement in processing and exploiting census statis

tics, there is an increased interest in adding topics to those historically covered by the popula-

tion and housing census. Because of additional costs and burden on the respondents, imposing

a long questionnaire on the total population, in many cases, does not seem to be appropriate.

Hence, countries often decide to broaden the scope of the census by covering additional top

ics through the use of sampling methodology. In this approach, two questionnaires are used:

(a) a short questionnaire containing only those questions intended for universal coverage and

(b) a long questionnaire containing detailed questions on the speciﬁc census topics.

3.10. Use of a sampling methodology in conjunction with full enumeration requires care

ful planning for determining the topics for the long questionnaire. is approach might be

cost-eﬀective, considering less duration of data collection for all topics; on the other hand, it

may create some complications regarding ﬁeld organization.

3.11. e following paragraphs explain how a sampling can be integrated with the full

enumeration and its possible advantages and limitations.

3.12. e expanded needs in most countries for extensive and reliable data have made the

use of sampling a cost-eﬀective part of census taking. Sampling is increasingly being used to

broaden the scope of the census through asking a number of questions of only a sample of the

population and households. is use of sampling makes it feasible to obtain urgently needed

data of acceptable precision when factors of timing and cost would make it impractical to

obtain such data on a complete count basis.

Part four of these Principles

and Recommendations focuses

exclusively on core and non-core

topics for population and hous-

ing censuses.

81Census operation activities 81

3.13. e suitability of particular questions for a sample enumeration depends on the preci-

sion with which results are needed for small areas and small population groups, and on the

enumeration costs involved.

3.14. It is important to bear in mind, however, that national legal requirements may make

it mandatory to collect certain information on a complete count basis. Legislation in many

countries prescribes complete population enumerations at particular times or makes certain

political or administrative dispositions dependent on particular results from a complete enu

meration. For example, the apportionment of seats in the legislature among the civil divisions

of a country often depends on the number of persons actually enumerated in each division.

e data needed for this and similar purposes may not be collected by sampling.

3.15. Census information that is collected for only a sample of the population or housing

units is usually obtained by one of two diﬀerent methods. e ﬁrst predesignates a systematic

subset of census households to receive a so-called “long” questionnaire, or the census form

that contains the detailed questions on all topics. Depending on the sample requirements,

which in turn take account of considerations of cost and precision, the systematic subset that

is designated for the long questionnaire may represent, for example, 1 in 4, 1 in 5, or 1 in 10

of census households. Under such a sampling scheme, all other households in the census will

receive a short questionnaire containing only those questions intended for universal cover

age. If countries choose this option, it is recommended that the predesignation of the sample

households that are to receive the long questionnaire be carried out at a central location by

supervisory statistical staﬀ, since it has been shown that when the enumerators themselves

actually identify the sample households the results are often biased.

3.16. e second method of sampling often used involves designating a sample of enumera

tion areas to receive the long questionnaire. In this approach, all households in the designated

enumeration areas receive the long questionnaire and all households in the remaining enu

meration areas receive the short questionnaire. e advantage of the ﬁrst method over the

second is that the sampling precision of results is greater because clustering eﬀects increase the

sampling variance when whole enumeration areas are used as sampling units. On the other

hand, the advantage of the second method is that diﬀerent enumerator staﬀ may be trained

more easily, since one set of enumerators can be trained only for the long questionnaire and

the other set only for the short questionnaire.

3.17. It is important to make certain that asking questions that are not asked of all persons

does not give rise to legal, administrative or even political issues, since census information is

required under statute and often with penalty for refusal.

3.18. e unit of enumeration

is an important element for preparation of designing the

census questionnaire, as each question aims to collect data for a speciﬁc unit of enumeration.

e census questionnaire can be successfully structured if it is done based on the units.

3.19. ere is broad consensus on the following separate sections in the census questionnaire:

i. Persons living in housing units;

ii. Persons living in collective living quarters;

iii. Households;

iv. Housing units;

v. Dwellings;

vi. Buildings;

vii. Agriculture.

For more information about

the units of enumeration, see

chapter IV.

Principles and Recommendations for Population and Housing Censuses, Revision 382

3.20. While designing the census questionnaire, the questions referring to a speciﬁc unit of

enumeration should be given in distinguishable format. is structure has a positive impact

in terms of better understanding of the meaning of the questions and carrying out the inter

view smoothly.

(d) Questionnaire design

3.21. Although a majority of countries are still using face-to-face interviews with paper

questionnaires, many countries have started to explore multimodal enumeration methods.

Some of these methods are: face-to-face interview with an electronic questionnaire, telephone

interview, self-enumeration with a paper questionnaire collected by enumerators, self-enu

meration with a paper questionnaire returned by mail, self-enumeration via the Internet,

enumeration and technology used for data capture are among the main factors aﬀecting the

design of the questionnaires. For example, the design of the questionnaires that will be used

for the face-to-face interview and self-enumeration will diﬀer, as the former will be applied

through enumerators while the latter will be directly used by the respondents. Whatever

methods are chosen, these need to be tested and assessed in advance for data quality and

feasibility. It is also important that data security and conﬁdentiality is maintained whatever

modes or approaches are used.

3.22. e design of the questionnaire must be based on the type of data collection mode

and approach used. Questionnaire design should also be based on the approach for data pro

cessing, for example whether data processing will be done through scanning, manual entry

or electronic transmission to the database.

3.23. e following paragraphs relate only to those approaches that involve direct enumera

tion of the individuals covered by the census. While many of the principles of designing

a statistical questionnaire will also apply to the design of the administrative instruments

underpinning a register-based approach, those instruments may also be based upon speciﬁc

requirements of the administrative programmes they address.

3.24. Further, where countries utilize the Internet or handheld devices to collect their cen

sus information, or a portion of that, the layout and organization of the data collection instru-

ment may diﬀer from that of the paper questionnaire. It is important to note that most often,

adopting an Internet approach also means moving from an enumerator-based approach to a

self-completion approach. e questions must be designed to be completed by the respond

ent without outside assistance. erefore census management should involve the information

technology team right from the questionnaire preparation stage. While many of the same

principles (for example clarity of wording, omission of unnecessary material) will apply also

to an Internet-based or handheld device-based collection of information, specialized advice

should be sought regarding such issues as (a) the technology employed to present the ques

tions to the respondent; (b) the method of capturing the response; and (c) quality assurance

checks employed during the capture process.

3.25. A crucial principle is that questionnaire design must be regarded as part of an inte

grated process of satisfying user demands by collecting, processing and disseminating infor-

mation provided by respondents.

3.26. e type of questionnaire, its format and the exact wording and arrangement of the

questions require most careful consideration, since the handicaps of a poorly designed question

naire cannot be overcome during or after enumeration. Among the many factors that should

be taken into account in designing the questionnaire are the method of enumeration, the type

of questionnaire (see paragraphs 3.9-3.17), the data to be collected, the most suitable form and

arrangement of the questions, technologies used and the processing techniques to be employed.

83Census operation activities 83

3. 27. e method of enumeration—in particular, whether the form is to be canvassed

and ﬁlled by the enumerator or by the respondent (see paragraphs 3.119-3.124)—governs to

some extent the type of questionnaire that can be used (for example, single individual, single

household or single set of living quarters, multiple household or multiple living quarters,

combined population and housing). It may also impact where each type of questionnaire

can be used, the framing of the questions and the amount of explanatory material that must

accompany them.

3.28. It is important that questions and response options are free from ambiguity. Moreover,

questions should not be oﬀensive; in many cases this can be avoided by excluding extremely

sensitive topics from the census questionnaire, but care must always be taken to consider the

reaction of respondents when designing questions. In addition, it should be noted that the

quality of information collected in a census will be reduced if the questionnaire is excessively

long. ese issues should be carefully assessed during the testing programme, including

the cognitive test and the so-called “pilot” census (see paragraphs 3.113-3.114) since poorly

worded questions not only will collect poor-quality data, but, by confusing respondents or

enumerators, may also impact subsequent questions in the questionnaire.

3.29. Special provision will have to be made if two or more languages are used in the

country. Several methods have been used to deal with this situation, such as (a) a single,

multilingual questionnaire; or (b) one version of the questionnaire for each major language;

or (c) translations of the questionnaire in the various languages available in the enumerators’

manual or on the Internet site for the census. Information on the distribution of languages

in the country is important for sound census planning and, if not available, will have to be

collected at some stage of the census preparations. Staﬀ recruitment and training procedures

(see paragraphs 2.119-2.124) will also have to take language issues into account.

3.30. If the housing census and the population census are to be carried out concurrently,

it will be necessary to consider whether a single questionnaire should be utilized to collect

information on both population and housing topics. If separate questionnaires are used,

they should be uniquely identiﬁed in a way that links the component forms so as to permit

subsequent matching, both physical and automated, of the data for each set of living quarters

with the data that refer to the occupants thereof. is will be particularly important where a

single housing form is used to cover separate personal forms for each individual.

3.31. When paper questionnaires are used for data collection, the use of processing tech

niques, such as optical mark reading and intelligent character recognition, will have a signiﬁ-

cant eﬀect upon the questionnaire design (see paragraphs 3.175-3.177). In the case of optical

mark reading, it is necessary both to allow for the spacing of response areas and to ensure

printing is undertaken to precise tolerances so that the data capture software is able to cap

ture all required data but not any of the material around the designated response areas. With

regard to intelligent character recognition, it is crucial to allow suﬃcient room for response

areas and to ensure that these are designed according to the requirements of the processing

system so that each response box contains only one character, and that the character is cor

rectly formed (usually in upper case). As noted in paragraph 3.30, where the scanning process

requires that a booklet questionnaire is separated into component pages, it is important that

some form of linking (for example by serial numbers or barcodes) is employed to ensure that

the correct information is amalgamated in the computer records.

3.32. Questionnaire design must be driven by a planning process based upon dialogue

between the statistical agency and those demanding information. Information to be collected

should respond to user needs both at national and international levels and therefore user

consultation is crucial in this regard. Previous census questions that are no longer relevant

should be dropped, as these do not add any more value. is is essential if the questionnaire

Principles and Recommendations for Population and Housing Censuses, Revision 384

is to be designed to provide the information needed by users. is will, in turn, determine

the tabulation programme, as it is to some extent conditioned by the limitations imposed by

the questionnaire.

3.33. e ﬁnal questionnaire must be drafted in time to allow for printing and developing

the data collection application, in the case of using electronic questionnaire (making allow

ance for the many contingencies, such as industrial action, breakdown of printing equipment

or delay of programming activities, that can arise in these processes); undertaking quality

assurance checks to ensure the printing is of suﬃcient quality to be used in the data capture

regime and the data collection application is running correctly under the data entry rules;

adequate training of census oﬃcials at all levels; and adequate publicity to be generated on

the content.

3.34. As some countries are also utilizing Internet portals and handheld devices for con

ducting the census, suﬃcient time must be given to design, develop, test and implement bug-

free e-questionnaires and related software systems. Last-minute inclusion or changes in the

questionnaire may aﬀect the overall quality of the programs, and in turn the census results.

3.35. In view of the many issues to be addressed in designing a census questionnaire, it is not

feasible to suggest speciﬁc model questions for the census topics covered in part two. How

ever, images of all census questionnaires that have been made available to the United Nations

Statistics Division have been placed on the Division’s website (see http://unstats.un.org/unsd

/demographic/sources/census/censusquest.htm) together with research papers relating to

questionnaires used to collect information on the various topics recommended for collection

and also using the diﬀerent technologies (Internet, handheld devices).

III. Building census infrastructure

3.36. e traditional population and housing census requires a concentrated eﬀort to build

the intricate and complex infrastructure that is suitable for conducting massive activities

simultaneously. is infrastructure refers to: the development of the census instrument ques

tionnaire; logistic schemes for disseminating and collecting returns; processing, editing and

validation; and dissemination of statistics. It also requires well-deﬁned workﬂows, and testing

of the production system as well as of the whole statistical business process.

3.37. Census infrastructure has to be put in place long before the data collection exercise

itself, as all of the components need to be extensively tested in circumstances that are as real

as possible. e importance of testing cannot be overestimated, especially in the context of

the need to build process components for processing and analysing data.

3.38. Building census infrastructure should be based primarily on the experiences and

lessons learned from the previous census. If the previous census took place a long time ago

and the documentation and institutional memory are not suﬃcient, putting together census

components should rely on statistical practice in conducting large surveys and on the schemes

for developing and implementing a statistical business process.

3.39. Particular components of the census infrastructure may already be available within

the national statistical oﬃce—for example, the statistical network of ﬁeld oﬃces covering the

country’s territory and staﬀ experienced in collecting and producing statistics. Others will

need to be built from the beginning, such as the training synopsis and schedules, recruitment

procedures and logistical arrangements. Methodical planning is, needless to say, critical in

85Census operation activities 85

this process of building census infrastructure, and developing Gantt charts early on would

signiﬁcantly facilitate managing the process in a holistic manner.

3.40. In that context, clear and unambiguous delineation of responsibilities in terms of

management is equally important with regard to the building process. Managers and super

visors need to have a comprehensive assignment from the very beginning and at all levels of

managing. While improvising may be necessary in certain circumstances, all eﬀorts should be

put into anticipating risks and developing and testing strategies to allow managers to mitigate

them and have alternatives at the ready.

3.41. In building new components of the census infrastructure—for example, outsourc

ing—it would be necessary to liaise with other parts of the government that may have more

extensive experience in that respect. In most cases, government not only would have extensive

experience—such as subcontracting for defence purposes —but also might have the capac

ity to provide goods and services that are needed. erefore, the process of building needs

to ﬁrst screen carefully and methodically existing government capacities, and then extend

beyond them.

3.42. e process of building has to be completely ﬁnished before the pilot census takes

place. Certainly, parts or perhaps even whole components of the infrastructure might need

to be adjusted and altered as a result of the pilot census; yet, that would represent a much

easier task than facing the consequences of not having had the components in the ﬁrst place.

3.43. Once the census takes place, all the steps in building the census infrastructure and its

testing need to be meticulously documented and stored for future use. Certain components

will certainly remain permanently as part of the broader national statistical infrastructure,

such as computers and similar devices. However, documenting in a comprehensive manner

is of paramount importance, not only for future censuses, but also for a better understanding

of the one that has just taken place.

IV. Mapping and geospatial data

A. Strategic planning

3.44. Mapping has been an integral part of census taking for a long time. Over the years,

census maps have played a critical role in all processes from preparation to dissemination of

census results.

3.45. e census-mapping programme should be developed at a very early stage of census

planning, considering the conditions and available resources of the country. Countries should

evaluate available mapping options by considering the following factors: (a) available geo

graphic resources; (b) requirements for new technologies and approaches; (c) available funds

and the allocated time frame; (d) staﬀ capacity needed for new approaches; and (e) require

ments for developing an ongoing geographic system. Evaluation of these factors will deter-

mine the best mix of technology and other approaches for each individual case.

3.46. ere are various options for mapping techniques. For example, traditional map

ping techniques have been used successfully in many countries and are still relevant in some

countries or at least some parts of many countries, particularly in remote areas. On the other

hand, with the recent development in technology, countries are motivated to develop digital

mapping techniques and improve the quality of census operation. Application of new tech

nologies requires more careful and long-term operational and managerial plans based on a

realistic assessment of costs and human resources required. In the case of not having internal

Principles and Recommendations for Population and Housing Censuses, Revision 386

capacity, the activities that need to be outsourced should be examined carefully before decid-

ing the possible options for census-mapping programmes.

3.47. Major technological advances include the widespread availability of personal comput

ers, handheld devices, global positioning system (GPS) and geographic information system

(GIS) software, and low-cost aerial and satellite imagery. ese advances have put new tools in

the hands of national statistical organizations to collect more accurate and timely information

about their populations. At the same time, it is recognized that adopting such new methods

would require long lead times for building capacity and organizational restructuring.

3.48. ere is widespread recognition that it is important for national statistical agencies

to develop a continuing mapping capability to serve their specialized mapping needs. Such

a capability can make a major contribution to the population and housing census and other

elements of the national statistical system. A continuing mapping capability within the sta

tistical agency can also contribute to the analysis and presentation of census results.

3.49. In the process of creating or updating census maps, census organization should col

laborate with other relevant agencies. Statistical agencies are usually not mapping agencies

and should not, for the most part, try to duplicate the functions of one. Likewise, mapping

agencies are not statistical agencies and often may not fully appreciate the statistical value of

the information they hold or how best to present statistical information in map-based prod

ucts. Despite this, undertaking a census can provide a catalyst for statistical and mapping

agencies to work together to the beneﬁt of both agencies and the community. Even more

importantly and at both the global and regional levels there is a continuing initiative to ensure

complete integration of statistical and geospatial information as a critical piece of national

systems for providing a comprehensive overview of many social, economic and environmental

phenomena. e ultimate goal is to develop a global statistical-geospatial framework that

would make accurate, authoritative, reliable geospatial information readily available to sup

port national, regional and global development.

3.50. While there is a range of techniques and technologies available for use in a census-

mapping exercise, the following sections do not make recommendation as to which system

would be most appropriate for speciﬁc countries. ese recommendations aim at presenting

and elaborating on essential principles for developing and implementing an eﬀective mapping

component of the census infrastructure.

B. The role of maps in the census

3.51. e role of maps in the census process is to support enumeration and to present

aggregate census results in cartographic form. Very few enumerations during the last several

census rounds were executed without the help of detailed maps.

3.52. In general terms, mapping serves several purposes in the census process, as follows:

(a) Maps ensure coverage and facilitate census operations (pre-enumeration). e

census oﬃce needs to ensure that every household and person in the country is

counted and that no households or individuals are counted twice. For this pur

pose, census geographers partition the national territory into small data collection

units. Maps showing enumeration areas thus provide an essential control device

that guarantees coverage of the census.

(b) Maps support data collection and can help supervise census activities (during

enumeration). During the census, maps ensure that enumerators can easily iden

tify their assigned geographic areas, in which they will enumerate households.

Maps are also issued to the census supervisors assigned to enumerators to support

The United Nations Global

Geospatial Information Manage-

ment (UN-GGIM) initiative was

launched by the Statistical Com-

mission of the United Nations to

assist governments in improving

policy, institutional and legal

frameworks for developing

eﬀective strategies to build

geospatial capacity in develop-

ing countries. For more details,

see http://ggim.un.org.

87Census operation activities 87

planning and control tasks. Maps can thus also play a role in supervising the

progress of census operations. is allows supervisors to strategically plan, make

assignments, identify problem areas and implement remedial action quickly.

enumeration). e cartographic presentation of census results provides a powerful

means for visualizing the results of a census. is supports the identiﬁcation of

local patterns of important demographic and social indicators. Maps are thus an

integral part of policy analysis in the public and private sectors.

3.53. e census enumeration team needs to have a set of unique maps covering the entire

country that accurately deﬁnes the boundaries within which each enumerator has to work

during the enumeration phase of the census. erefore, the quality of maps used in the census

has a major inﬂuence on the quality and reliability of census data.

3.54. e types of maps required for census management include the following: (a) small-

scale reference maps for use in the census agency to manage the overall operation; (b) large-

scale topographical maps for use by enumerators; and (c) maps of the subregions or adminis

trative areas, for the use by managers, showing the location of small population settlements

and dominant physical features, such as roads, rivers, bridges and the type of terrain. e use

of satellite imagery to generate these maps is now increasingly common across countries.

3.55. Careful consideration should be given to organization and management of map-

ping activities during the census planning and preparation phases. e lead time necessary

for creating, printing and distribution of maps for a country will be determined by a wide

range of factors, including the number of maps to be produced, the technology available to

produce them, the availability of funds to acquire additional resources and the time required

for distribution of the maps to ﬁeld staﬀ.

3.56. It is still the case that in many countries there are only a limited range of maps avail

able, and these often do not show suﬃcient detail to enable the boundaries of small areas to

be clearly deﬁned. is is particularly likely to apply in areas of unplanned settlement. It is

thus common to supplement the maps with other material, such as (a) lists of households,

preferably compiled by statistical agency staﬀ as part of the process of delineating enumera

tion areas, but on occasion provided by local leaders (see paragraphs 3.115-3.118); or (b) a

textual description of the boundary, including roads, railway lines, power lines, rivers and

other physical features. is description may also include obvious landmarks on the boundary

(school buildings, water points and other reference features).

3.57. Previous experience has shown that relying entirely on a list of households, written or

verbal descriptions and directions, or local knowledge of the area boundaries will often lead

to confusion and error because people tend to have mental images of places that may not align

with the area as it is really reﬂected in the design of the enumeration area. Similarly, the super

visor’s mental map of an enumeration area may diﬀer markedly from that of an enumerator.

To overcome such problems, it is important that the best possible quality maps be the basis

for census enumeration operations and that the collection staﬀ receive comprehensive training

in the correct use of the maps and associated textual material if that is provided.

C. Census geography

3.58. Prior to developing the mapping programme for the census, consideration needs to

be given to the geographic classiﬁcation to be used and the mapping infrastructure avail

able to carry out the mapping tasks. As the geography on which the census is collected will

determine the geography on which the census data can be disseminated, a geographic clas

It may be noted, however,

that hand-drawn maps by the

enumerators demarcating

the enumeration area with all

the houses and other physical

features such as roads and rivers

continue to have their utility in

countries where the enumera-

tion area boundary is provided

to enumerators by description

rather than through pregener-

ated maps.

Principles and Recommendations for Population and Housing Censuses, Revision 388

siﬁcation should be devised in conjunction with the development of census mapping. e

publishing of this geographic classiﬁcation by the national statistical oﬃce so that it can be

reused throughout the statistical system and for administrative purposes will increase the

value of census data as they will be more relatable to other information. e details of design

ing a general geographic classiﬁcation, including the deﬁnition of the various areas of the

geographic classiﬁcation and their relationship to one another, are more complex than those

involved in census mapping and will not be covered further in this chapter.

However, the

design of enumeration areas and other census management areas is of crucial importance for

the census and is outlined in the following paragraphs.

3.59. It is of critical importance to ensure that the boundaries of various administrative

units are frozen at least six months in advance of the census date so that no further jurisdic

tional changes are eﬀected until the enumeration is over. is would be of considerable help

in delimiting enumeration areas and minimizing chances of omission or duplication.

(a) Administrative hierarchy

3.60. One of the earliest decisions in census planning pertains to the administrative areas

for which census data will be reported. Administrative areas can be any special geographic

unit, but mainly they are units of administration, that is, some governmental authority has

jurisdiction over the territory. Census preparation involves creating a list of all administrative

and statistical reporting units in the country. e relationships among all types of adminis

trative and reporting unit boundaries should be deﬁned. Every country has its own speciﬁc

administrative hierarchy, that is, a system by which the country and each lower-level set of

administrative units (except the lowest) are subdivided to form the next lower level.

3.61. Only some of these hierarchical levels may have actual administrative roles; for exam

ple, the province, district and locality levels may have capitals with local government oﬃces

that are responsible for those regions. Other units may have statistical roles alone; that is, they

are designed for the display of data and not for administering territory. In some instances,

however, administrative units may not be completely nested. Especially when considering

both administrative and other statistical reporting units, the census oﬃce may need to deal

with a very complex system of geographic regions.

3.62. In some regions, the establishment of a deﬁnitive list of units is a major operation

because of diﬃculties arising from the frequent fragmentation, disappearance or combination

of small localities, and from changes in name, variations in spelling, the existence of more

than one name for the same place or the use of identical names for diﬀerent places. is list

ing should be held as a formal database or as an integral component of the databases forming

part of a geographic information system.

(b) Delineation of enumeration areas

3.63. Whether manual or digital cartographic techniques are used, the delineation of enu

meration areas is similar. e design of enumeration areas should take various criteria into

account. Correctly delineated, enumeration areas will:

(a) Be mutually exclusive (non-overlapping) and exhaustive (cover the entire country);

(b) Have boundaries that are easily identiﬁable on the ground;

(d) Be compact and have no pockets or disjoined sections;

(e) Have populations of approximately equally size;

(f ) Be small and accessible enough to be covered by an enumerator within the census

period;

For a full elaboration and details,

please see Handbook on Geospa-

tial Infrastructure in Support of

Census Activities (United Nations

publication, Sales No. E.09.

XVIII.8).

For further details on GIS

mapping, see Handbook

on Geospatial Infrastructure

in Support of Census Activities

(UnitedNations publication,

Sales No. E.09.XVIII.8).

89Census operation activities 89

(g) Be small and ﬂexible enough to allow the widest range of tabulations for diﬀer-

ent statistical reporting units (if enumeration areas are being used as the basis of

dissemination geography);

(h) Be useful for other types of censuses and data collection activities as well.

3.64. e size of enumeration areas can be deﬁned in two ways: by area or by population.

For census mapping, population size is generally the more important criterion, but surface

area and accessibility also have to be taken into account to ensure that an enumerator can

service an enumeration area within the time allotted. e chosen population size varies from

country to country and is generally determined on the basis of pretest results. Average popula

tion size may also vary between rural and urban areas since enumeration can proceed more

quickly in towns and cities than in the countryside. Under special circumstances, enumera

tion areas that are larger or smaller than average may have to be deﬁned.

3.65. Before delineation of enumeration area boundaries, the number of persons living in

an area and their geographic distribution needs to be estimated. Unless there is information

from a recent survey, registration system or some other information source, these numbers

need to be determined by counting the housing units, determining the associated number

of households and multiplying by an average household size. e number of housing units

can be determined through cartographic ﬁeldwork, cooperation with government oﬃcials,

extrapolation from previous census results or by means of aerial photographs or satellite

imager y.

3.66. Enumeration area boundaries need to be clearly observable on the ground. Even if

they do not have considerable geographic training, all enumerators need to be able to ﬁnd the

boundaries of the area for which they are responsible. us, population sizes between enu

meration areas may be varied in order to produce an easily identiﬁable delineation. Natural

features that can be used for this purpose are roads, railroads, creeks and rivers, lakes, fences

or any other feature that deﬁnes a sharp boundary.

3. 67. Procedures for delineation of enumeration areas should be developed that will allow

comparability of areas from one census to the next. Change analysis at the local level is greatly

facilitated if the units of enumeration remain compatible between censuses. A unique code

should be assigned to each enumeration area and the changes (for example in the case of

splitting areas with a high level of growth) should be tracked. e statistical oﬃce is often the

custodian of coding schemes in the country and should also be the focal point for the design

of the census-mapping codes. In cases where this is not possible, the criteria can outline design

principles that will allow users to easily compare enumeration-area-based data across censuses.

When the population and housing census are conducted separately, eﬀort should be made to

use the same enumeration area frame for both censuses as far as possible.

3.68. Supervisory areas provide the means for a group of enumerators to be eﬀectively

managed. After delineation of enumeration areas, the design of supervisory maps is usually

straightforward. Supervision areas consist of groups of contiguous enumeration areas that

share some of the same characteristics as enumeration areas. e enumeration areas assigned

to the same supervisor should be compact, in order to minimize travel times, and of approxi

mately equal size. ey should be included in the same ﬁeld oﬃce area, which usually is

deﬁned according to administrative units.

Principles and Recommendations for Population and Housing Censuses, Revision 390

(d) Delineation of census management areas

3.69. Census management areas will consist of aggregations of supervisory areas brought

together for ease of managing the enumeration staﬀ. Where existing government staﬀ and

structure are used for enumeration purposes, the census management areas may be the same

as the administrative regions. It should be noted that this may be a matter of administrative

convenience and the particular hierarchy (or way of combining enumeration areas into larger

areas) for this purpose need not necessarily be the same as that for the dissemination phase,

which must be driven by the needs of users. However, the greater the congruence between

enumeration areas and pre-existing administrative boundaries, the easier is the task of con

ducting the census.

(e) Geographic coding

3.70. e coding of each housing or population unit to a small atomic area, often the enu-

meration area, or to a speciﬁc longitude and latitude, allows for ﬂexible production of diﬀerent

geographic tabulations of outputs, and production of comparable area-based geography over

time. Two somewhat diﬀerent approaches are available for coding the location of housing or

population units. e ﬁrst approach is to code all units to the lowest-level enumeration area,

sometimes referred to as the “enumeration district”. e second approach, which at greater

cost permits ﬁner geographic speciﬁcity, is usually based on some coordinate or grid system,

such as that of latitude and longitude.

3.71. A digital geographic database in vector format consists of a structured set of points,

lines and polygons. Each geographic feature—each point, line or area—has a unique identi

ﬁer that is used by the system internally. is internal identiﬁer is not usually accessible by the

user and should not be modiﬁed externally. A more meaningful identiﬁer is needed that can

be used to link the geographic features to the attributes recorded for them. For the enumera

tion areas and administrative units, this link is the unique enumeration area or administra-

tive identiﬁer, which is listed in the master ﬁle of all geographic areas relevant in the census.

3.72. Indeed, a unique code needs to be assigned to each enumeration area. is code is

used in data processing to compile enumerated information for households in each enumera

tion area and to aggregate this information for administrative or statistical zones for publica-

tion. is is the numerical code that provides the link between the aggregated census data

and the digital enumeration area boundary database stored in the case of using GIS. e

coding scheme needs to be determined on a country-by-country basis, ensuring codes are

unambiguous, and should be designed in collaboration with the national statistical oﬃce.

e most important principles in the design of a coding scheme are ﬂexibility, expandability

and compatibility with other coding schemes in use in the country. e statistical oﬃce is

often the custodian of coding schemes in the country and should also be the focal point for

the design of the census-mapping codes.

D. Technology for census mapping

3.73. Before census mapping commences, the census agency needs to determine the appro-

priate technology for mapping. Countries need to choose technologies to improve eﬃciency

of census operations, data quality and timeliness, balancing these with cost factors in view of

their national needs and circumstances. e application of technology must also ensure that

conﬁdentiality of data is maintained.

3.74. In general, countries need to approach the use of technology for mapping as a continu

ous process rather than merely a sequence of mapping and dissemination operations. Use and

application of geospatial technologies and geographic databases are very beneﬁcial to improv

This section draws heavily

upon material in Handbook

on Geospatial Infrastructure

in Support of Census Activities

(UnitedNations publication,

Sales No. E.09.XVIII.8).

91Census operation activities 91

ing the overall quality of census activities at all stages of the census. Major technologic al

advances include the widespread availability of personal computers, handheld computers and

personal digital assistants, GPS and GIS software, and low-cost aerial and satellite imagery.

ese advances would be of interest to national statistical organizations to collect more accu

rate data in a timely manner.

3.75. In circumstances where it has not been possible to acquire appropriate base maps

for areas of geography, enumerators (or other enumeration staﬀ) may produce hand-drawn

maps, accompanied by a textual description of the boundary features, to enable a successful

enumeration. Hand-drawn maps do not possess the level of accuracy oﬀered by high-quality

topographical maps, but are an option when maps for an area (a) do not exist; (b) are at too

small a scale to provide suﬃcient detail for an enumeration area map; or (c) are seriously out

of date and cannot be updated in the time available.

3.76. Where reasonable-quality topographical maps are available, they should be used as a

base, and hand-drawn enumeration area boundaries can be added as an overlay on transpar

ent ﬁlm, and the combination photocopied for use by the enumerators. Alternatively, the

enumeration area boundaries could be hand-drawn on the printed map, and the result can

be used further. However, either of these kinds of combination maps need to be used with

caution; ﬁeld personnel need to be aware that the maps could possibly have errors or incon

sistencies, which it is their responsibility to resolve and record when in the ﬁeld. All base

maps produced for the census should be referred to a unique, consistent, geodetic reference

system all over the country.

3.77. Where accurate and current maps at relevant scales are not available for a country or

part of a country, the technological alternatives described in the following paragraphs could

be employed subject to consideration of the constraining factors described in paragraphs

3.79-3.82:

(a) Satellite images. A satellite image typically covers a large area and can be cost-

eﬀective compared to other sources. Imagery should be preprocessed by the sup

plier so that it is rectiﬁed and georeferenced (a known scale and orientation, with

some latitudes and longitudes, is printed on the face of the image). Satellite image

data have gained in volume, popularity and ease of use. Satellite imagery, if used

pragmatically, can save countless person-hours by focusing attention on critical

areas. Remote sensing data can be used as an independent check on the ﬁeld

veriﬁcation process.

(b) Aerial photography. Acquisition of aerial photographs for large areas of a country

may be expensive. However, existing archives of photographs can be an excel

lent resource for preliminary counts of dwellings and as a base for basic maps.

In some cases digital aerial photographs can be a cost-eﬀective way of initiating

some components of a GIS.

for use by enumerators in the ﬁeld can be greatly assisted by GPS. A simple,

handheld GPS receiver will give latitude and longitude coordinates with reason

able accuracy of key points. Depending upon the system selected, a GPS may also

track linear features and thus be useful for mapping boundaries. Maps printed

from a GIS or hand-drawn map can be enhanced by the addition of latitudes and

longitudes recorded at key points to provide orientation, scale and absolute posi

tion. Such information will be particularly valuable for dissemination purposes or

if the work is a component of developing a GIS for later use. e ability to record

information directly without transcription has the beneﬁt of removing several

intermediate steps. Coordinates are captured and immediately displayed on the

Principles and Recommendations for Population and Housing Censuses, Revision 392

portable computer screen, and if a digital base map is available, the coordinates

can be displayed on top. Field staﬀ can add any required attribute information

and store these data in a geographic database at the home oﬃce. Given that note

book computers and other portable computing devices are becoming less expen-

sive, integrated ﬁeld-mapping systems are becoming a viable option for ﬁeld data

collection for census purposes. Advances in technology, including GPS, wireless

communication and computer miniaturization, have made possible numerous

new applications for handheld GIS, particularly the development of specialized

software for census ﬁeldwork.

(d) Georeferenced address registry. A high-quality, comprehensive, updated and geo

referenced address registry of each building and dwelling can give great support

in planning and organizing a census. A georeferenced list of addresses can play

a central role in many ﬁeldwork operations and will provide the key to accurate

delivery, collection and follow-up of questionnaires. e best way to associate each

address with a location in physical space of a map is to specify its coordinates in

a proper geographic reference system. With geographic coordinates addresses can

be entered in available maps or into the GIS. If it is not possible to get coord inates

it is recommended at least to geocode addresses. Geocoding is the process of ﬁnd

ing associated geographic coordinates from other geographic data. For example, as

geographic coordinates of an address, the coordinates of the centre point (centroid)

of the enumeration areas to which the address belongs could be taken.

3.78. Where a digital base map is prepared, this may be used in conjunction with a GIS

technology as the basis for coding information supplied in the census. is could apply to

address of usual residence now and/or in the past, place of work and similar topics.

3.79. e implementation of strategies using such technologies must be thoroughly planned

with the guidance of qualiﬁed staﬀ or external experts with formal qualiﬁcations in the use

of advanced mapping technology. It is particularly important that the cost of acquiring and

maintaining the hardware required to use this technology is factored into the budget (and

a sound cost-beneﬁt analysis undertaken to support such changes), and adequate plans are

made to ensure the availability of suﬃcient quantities of hardware in time for the census.

3.80. It should be noted that there might be additional risks due to the need for equip

ment to be operated in suboptimal conditions, including poor weather, dusty conditions or

poor lighting. Despite its versatility, GPS may not be able to diﬀerentiate the coordinates of

overlapping or closely located dwellings in multistorey buildings and in this circumstance

should only be regarded as providing coordinates for the building rather than the dwelling

units within it.

3.81. It is important to ensure that where such systems are employed, they are clearly

understood by enumeration staﬀ. is should be achieved by ensuring that the staﬀ, whether

at the cartographic update (pre-enumeration) stage or enumeration stage, are given adequate

training in the interpretation of the maps. Should the maps be incorporated in digital devices

such as personal data assistants, the staﬀ should be trained in the use of both the hardware

and the software.

3.82. As with all other signiﬁcant changes to census procedures, it is crucial that census

geographic and mapping processes are successfully included in tests prior to being used in the

main operation. is is particularly the case where a change in level of technology is being

considered.

93Census operation activities 93

E. Geographic information systems

3.83. A geographic information system can be seen as a system of hardware, software and

procedures designed to support the capture, management, manipulation, analysis, modelling

and display of spatially referenced data. In practical terms, such a system may range from a

simple desktop mapping facility to a complete GIS system that is capable of solving complex

planning and management problems or producing detailed georeferenced inventories. Its

ability to use space to integrate and manipulate data sets from heterogeneous sources can

make its application relevant to planning and managing the census process itself. For exam

ple, a GIS provides functions for the aerial interpolation of statistical data in cases where the

boundaries of aerial units have changed between censuses. However, the development and

implementation of such a repository of georeferenced data are not easy tasks to accomplish,

and simple desktop mapping systems generating thematic maps from a database of base maps

and indicators will satisfy the needs of most census organizations.

3.84. GIS technology should be considered only at a level appropriate to the skills and

resources available, and should constitute an integral part of the overall work of the organi

zation. Cooperative arrangements with other agencies should be pursued particularly with

regard to the acquisition and maintenance of base map data, which should not be the respon

sibility of the statistical organization. Statistical organizations should proceed with GIS devel-

opment or implementation only where it is feasible to maintain such a system during the

intercensal years and where there is no dependence on external support.

3.85. Statistical oﬃces may nevertheless develop GIS applications with population data

and other georeferenced data from other sources for more advanced forms of spatial analysis.

e task could be shared with other institutions, or be delegated completely to specialists

elsewhere. e role of the census oﬃce would then consist in supplying census data at the

right level and in the right format for such a system. Census oﬃces provide vital information

on current demographic conditions and future trends for policymakers in a range of sectors

such as health care, education, infrastructure planning, agriculture and natural resources

management; and the provision of spatially referenced census databases is a prerequisite for

the use of demographic data in these ﬁelds.

3.86. In this regard, it should be noted that the GIS should be capable of generating addi

tional geographic delimitations beyond those used in the census, such as school districts,

water catchment areas or power service units. ese entities will have to be constructed

from the smallest geographically identiﬁed units available in the census (for example block

faces, grid squares or enumeration areas). If (as is the case in most developing countries)

enumeration areas are the smallest unit, this will have important implications for the estab

lishment of enumeration area boundaries. Cooperation with the authorities responsible for

these geographic entities before the boundaries of enumeration areas are drawn can reduce

later problems.

3.87. Being a rather complex technology and a resource-consuming one, GIS needs to be

introduced in developing countries carefully and gradually. As an alternative to immediately

launching full-scale GIS applications, countries may start with a simple and robust design

that is likely to be understood and maintained by a wide array of users, transferable to a wide

range of software packages and independent of any hardware platform. GIS implementation

in a developing country may follow a hierarchical strategy, with the national statistical oﬃce

employing a high-end commercial GIS with extensive capabilities for handling and analysing

large amounts of spatial data. Widespread dissemination of databases can then be achieved by

creating a version of the ﬁnished databases using a low-end mapping software format for dis

tribution at low cost and through web dissemination of macroinformation in an online GIS.

Principles and Recommendations for Population and Housing Censuses, Revision 394

3.88. In recent years, many countries have adopted the use of GIS to facilitate census map-

ping in the production of both enumeration maps and dissemination products. As the cost is

declining and the basic technology is now well established, it is expected that this will con

tinue. It is likely that the census could be a useful catalyst for increasing capacity within the

statistical oﬃce (or the country as a whole). Adoption of GIS should thus be seen as a major

strategic decision with impacts beyond the census operation, and many issues need to be con

sidered. A GIS database, a census geographic database built at the enumeration area level, is an

important infrastructure for the national statistical oﬃce to manage, analyse and disseminate

census data, and monitor the continual change in geography between successive censuses. It

also constitutes a fundamental component of a national geographic information infrastruc

ture that allows the national statistical oﬃce and other national organizations to integrate

socioeconomic and environmental data for evidence-based decision-making.

A prerequisite

to the building of a geographic database at the enumeration area level is the development of a

geocoding scheme, whereby each enumeration has a unique code, an administrative identiﬁer

that can be used to link the geographic features to the attributes recorded for them.

3.89. e (potential) beneﬁts and costs of GIS are summarized as follows:

(a) Beneﬁts:

i. Closer linkage between maps for enumerators and map-based products for

users;

ii. Enriched dissemination of census data as they can be visualized in geo

graphic areas for easy understanding by users;

iii. e cost of intercensal updating of the base map will be less with a digital

base map, enabling among other things the construction and updating of

sampling frames;

iv. Producing duplicate maps may be less expensive with a GIS solution;

v. GIS will have increased ability to undertake quality assurance of geographic

boundaries;

vi. e census agency will have a greater ability to perform spatial queries and

advanced analysis under GIS;

vii. Space needed to store input maps for digital purposes will be far less.

(b) Costs:

i. GIS requires additional technical expertise;

ii. GIS will require a higher level of computing infrastructure;

iii. A clerical census system can proceed on the basis of basic maps. However,

use of GIS in this task requires that a digital map base exists. If it is neces

sary to create the digital map base, signiﬁcant lead times are required as

well as signiﬁcant funding. In both cases, more experienced technical staﬀ

are required;

iv. In most cases, the preparation of maps or GIS will not be the core business

of a statistical agency.

F. Contracting out for census mapping

3.90. e development of a mapping project beyond rudimentary clerical systems requires

considerable knowledge of mapping, cartography and geographic systems. In the event that

a census agency cannot draw on such skills from within the agency, it may be required to

contract out some or all of the elements of preparation of census maps.

See elaboration on GGIM in

paragraph 3.49 above.

For more information, see

the Handbook on Geospatial

Infrastructure in Support of Census

Activities (United Nations publi-

cation, Sales No. E.09.XVIII.8).

95Census operation activities 95

3.91. Mapping for ﬁeld purposes under a contract or agreement basis requires the statisti-

cal agency to specify its requirements and prepare clear terms of reference to the contractor.

ese may include the following: (a) acquiring the base map data; (b) creating (or obtaining)

the statistical boundaries and aligning them to the base map; (c) providing a process for enu

meration area designers to advise on changes to boundaries (and updates to associated spatial

data); (d) producing hard copy maps as speciﬁed for ﬁeldwork.

3.92. e statistical agency should undertake the enumeration area design work and valida

tion of the associated spatial data, as well as take delivery of the hard copy maps for quality

assurance checks and subsequent delivery into the ﬁeld. e statistical agency must also

accept full responsibility for the quality standards and delivery of the maps to ﬁeld staﬀ

as required. After the census, any feedback received from enumerators about the base map

should be communicated to the mapping agency.

3.93. Mapping for dissemination purposes may be more challenging because the outputs

will involve representation of statistical information (with, or as part of, a map) and will often

be accompanied by analysis or commentary about the information. Advances in mapping

software have made it easier for census agencies to produce a wide variety of standard the

matic maps. However, advanced mapping products may require the expertise of a contractor.

In these cases, it may be better for the statistical agency to focus on the statistics and let the

contractor provide the technical skills required to produce the actual products with tight

quality assurance procedures in place to ensure that the output from the contractor satisﬁes

the end user requirements described above.

G. Implementation of census-mapping programme

3.94. e development of a mapping system within the census agency requires the coord-

ination of a series of complex tasks with relatively long lead times. It is important that project

plans are established to manage this process. e main activities to be reﬂected in such plans

are discussed below:

(a) Establishing a mapping unit. e census-mapping project requires a special

ized project team. Where mapping activities are outsourced, the mapping pro-

ject teams will be responsible for specifying the requirements of the census for

mapping products and coordinating arrangements with the provider of mapping

services.

(b) Developing a timetable. e critical date is the date that maps must be delivered

to the ﬁeld. e mapping programme must commence early in the census cycle to

allow suﬃcient time to produce national coverage of maps well before the census

date and before training of ﬁeld staﬀ.

mapping project is establishing a base map of the country, including digital map

ping data if required. If a census-mapping project already exists, the agency may

still require updates to their existing map holdings.

(a) Sources and types of hard copy maps

3.95. Where a hard copy base map is to be used, oﬃcial published maps may be available

from national or provincial government mapping agencies, the local government or munici

pal bodies. Other sources of maps may be other government agencies or private companies.

Where the maps are obtained from sources outside the census agency, permission to use

the maps collected must ﬁrst be sought from the original source and any copyright issues

addressed.

Principles and Recommendations for Population and Housing Censuses, Revision 396

(b) Digital mapping data

3.96. When establishing a digital geographic database, a major consideration is the determi

nation by the census agency of data requirements. With increasing amounts of digital spatial

data becoming available, it is also important that standards and a common data speciﬁcation

be produced to ensure data validity and consistency.

3.97. e key rules to be followed in selecting data items for inclusion are to question

whether (a) the data item will be useful to enumerators in navigating their way around their

enumeration area; and (b) the data item is relevant to users. Assessing the utility of data

items to users in a census-mapping context must place signiﬁcant emphasis on the user needs

for small or customized areas. Data items that meet neither of those criteria should not be

included in the database.

3.98. Preparing or updating base maps, or the base map digital data, requires substantial

resources. e ﬁnal content of base maps will have a major bearing on the accuracy and

completeness of enumeration area maps and, subsequently, the eﬀectiveness of census enu

meration. e updating of base maps should be scheduled according to priorities, based on

areas in which changes to the number or characteristics of the people require the maps to be

updated. Important features to be updated include (a) accurately named and presented roads

and waterways; (b) administrative boundaries; and (c) landmark features, such as schools,

place of worship, post oﬃces, parks and large buildings.

(d) Operational design for enumeration and supervisory areas

3.99. Whether a hard copy or digital base is employed, an enumeration area design manual

should be produced that contains the design criteria and the procedures to be followed when

designing the enumeration area. e manual can be used as a basis of training for those

involved in the design process.

3.100. If possible, enumeration area design should be conducted by regional statistical oﬃce

staﬀ who are primarily responsible for enumeration areas in their province or region. is

ensures that local knowledge can be utilized in the design process. A considerable part of the

process is the gathering of information on where population and boundary variations have

occurred in order to determine the best way to design particular enumeration areas. As an

output of enumeration area design, a list should be produced that provides the enumeration

phase with all relevant ﬁeld data for each enumeration area, and the dissemination phase

with relevant geographic data.

3.101. e design of ﬁeld supervisor and management area boundaries can be determined at

the completion of the process through the aggregation of enumeration areas, and the alloca

tion of geographic identiﬁcation codes.

3.102. Quality assurance measures should be implemented to ensure that data are correct to

a minimum standard, both for ﬁeld navigation and for technical correctness in cases where

a digital base is to be used as an output medium.

(e) Printing and content of ﬁeld maps

3.103. Careful consideration should be given to the (considerable) time required for printing

maps when establishing the project plan for census mapping.

3.104. Maps should be provided to every level of ﬁeld staﬀ. If paper maps are used, at least

one map must be printed for every enumeration area in the country. It is recommended that

two copies of the map be produced, one copy to be used by the enumerator and the other

by the ﬁeld supervisor for training and reference purposes (and subsequently retained by the

97Census operation activities 97

statistical oﬃce as input to the following census cycle). e use of computer technology for

data collection, such as tablets, laptops and other handheld devices, may also be suitable for

displaying maps available to ﬁeld personnel.

3.105. Other considerations for the preparation of enumeration maps (whether based upon

hard copy or digital data) include the following:

(a) Enumerators may be required to navigate in poor lighting conditions and thus

details should be easily read;

(b) e maps must be easily interpreted with text and symbols readily identiﬁable

and correctly placed, along with the information being presented in a standard

format compared to other source maps;

be clear and unambiguous;

(d) Enumeration areas must be distinguishable when compared to the surrounding

area;

(e) Folding or refolding of large paper maps (larger than A2 in size) is ineﬃcient for

staﬀ;

(f ) Paper and digital maps need to facilitate the addition of written enumerator com

ments;

(g) Production of the maps should be cost-eﬀective;

(h) e maps should be suitable for reuse to meet dissemination purposes where this

reﬂects user demands.

3.106. Maps for supervisors or regional managers should be of smaller scale, providing suﬃ

cient detail to identify major features. When using paper maps those should not be so large as to

be diﬃcult to handle easily in the ﬁeld. In many cases, the use of inset or supplementary maps

may be required if the map is to cover a relatively large area. For all levels of senior ﬁeld staﬀ,

the maps should show the boundaries of all subsidiary units for which they are responsible.

H. Maps for dissemination purposes

3.107. Maps, which are now commonly in the form of digital products, play an increasingly

important role in the dissemination phase of the census. Statistics compiled from census

data can be geographically referenced and provide for methods of analysing the geographic

characteristics of those statistics. Maps may then be used eﬀectively to relate statistical data

to the geographic area to which the census results refer. is makes the statistics easier to

understand and more readily usable by both expert users and the general public.

3.108. If a complete digital census geographic database has been created, then statistical data

bases for administrative or statistical units can be produced simply through aggregation. For

the countries that do not use digital techniques for the production of enumeration area maps,

options still exist to develop a digital georeferenced census database at this stage for produc

ing publication-quality maps to accompany census reports, for distribution to outside users

who want to analyse census data spatially or for internal applications. is database can be

compiled for a suitable level of the administrative hierarchy or for other aggregated statistical

regions. At that level of aggregation, the resources required for producing a digital database

are much less than those necessary for a complete digital enumeration area map database.

3.109. A comprehensive elaboration of the use of maps for dissemination of census statistics

is presented in “Geographic products” under “Census data dissemination: products and ser

vices” (see paragraphs 3.349-3.366).

Principles and Recommendations for Population and Housing Censuses, Revision 398

V. Census tests

3.110. e testing of various aspects of a census plan prior to the enumeration is of critical

importance for all countries, and an essential one for countries without a long history of

census-taking, especially for those in which fundamental changes in census methods or use

of new technologies are being considered. Census tests can be designed for diﬀerent purposes

and in diﬀerent ways. To yield full beneﬁts, tests should be employed for all stages of the

census, including enumeration, processing and evaluation of results. Separate tests should

be conducted to test new technologies such as the Internet and handheld devices in order to

allow identifying problems linked to the data collection application design and architecture,

the data transfer system and the integrity and security of data transferred. Such tests can give

important information on the adequacy of the ﬁeld organization, training programme, extent

of respondent burden, processing plan, budget and other important aspects of the census.

ey are particularly valuable in probing for weaknesses in the questionnaire, in the instruc

tions or in enumeration procedures that might aﬀect the quality of the data. ey can be

designed to provide information on the relative eﬃcacy of alternative methods of enumeration

and technology, and on the average time required for enumerating a single household or a

single set of living quarters. Such information is useful in estimating staﬀ and cost require

ments. In addition, census tests serve as practical training for the nuclear staﬀ of supervisors

and other oﬃcials.

3.111. When carrying out census tests, probability samples of geographic areas or units are

not usually necessary. Since the purpose of the pilot census and pretest is to judge the opera

tional feasibility of a proposed course of action for the main census rather than make popula-

tion estimates, purposive samples can usually be used for such tests. Purposive selection of one

or a few geographic areas is generally preferable for such feasibility testing. Purposive samples

are also particularly useful when it is necessary to test census questionnaires and methods

in areas with particularly diﬃcult conditions. On the other hand, when overall quantitative

measures are needed for comparing eﬃciencies of diﬀerent procedures (for instance, in exam

ining the anticipated response errors arising from diﬀerent systems of enumeration), random

sampling procedures must be used.

3.112. e ﬁrst kind of tests carried out during census preparations are questionnaire tests.

eir purpose is to test the suitability of intended census questions, including their formu

lation and the instructions provided, as well as the suitability of the questionnaire design.

Such tests can be particularly helpful in assessing the suitability of the proposed material for

enumerating speciﬁc population groups, as well as the general public. ese tests are also used

for estimating the time requirements in enumeration. It is practical to carry out question

naire tests on a small scale in several purposively selected places. Because they are relatively

inexpensive, repeated rounds of questionnaire tests may be carried out until a satisfactory

questionnaire has been evolved. In this regard, testing the questionnaire using eye-tracking

technology is beneﬁcial to design questionnaires more scientiﬁcally as reading patterns of

respondents can be recognized technically through this test.

3.113. A comprehensive test of all census procedures is often called a “pilot census”. Such

large-scale tests should be designed and managed to thoroughly test the entire census infra

structure. Essential features of a pilot census are coverage of one or more sizeable adminis-

trative divisions and encompassment of the preparatory, enumeration and processing stages

of a census, by which it thus tests the adequacy of the entire census plan and of the census

organization. In order to best serve this purpose, care should be taken to ensure that condi

tions in the pilot census are as close to the conditions that would be present during the actual

enumeration as possible. For this reason, it is often taken exactly one year before the planned

99Census operation activities 99

census so as to conform to the expected seasonal patterns of climate and activity. It is gener-

ally unwise to consider the pilot census a source from which to derive usable substantive data.

Apart from the sampling problems involved, such a use inevitably detracts from the central

purpose of the pilot, which is to prepare for the main census.

3.114. It is critically important to undertake a set of tests of the information and communi

cation technology (ICT) solutions and production systems that are planned to be applied in

the census. Depending on the extent and characteristics of ICT, these tests should include all

ICT components related to the ﬁeldwork and to data transfer, entry and processing well ahead

of the census itself. is is particularly important if a new technology is being introduced,

such as the Internet, handheld devices or other electronic collection tools, and scanning the

questionnaires as a means of capturing data. Tests should include the testing of applications,

systems and the equipment itself, as well as the underlying circumstances necessary to avoid

equipment malfunctioning, such as climate, or signiﬁcant delays due to inadequate quality of

paper causing paper jams or unexpected problems in programming activities. In the context

of new approaches using electronic data collection, testing should include daily data transfers

to the major depository of data. Testing the eﬃciency of data entry rules, coding, editing and

tabulation applications should be done based on results collected by the pilot census.

VI. Living quarters and household listing

3.115. A list of sets of living quarters, structures containing living quarters or households that

are available at the start of the census is an instrument for the control of the enumeration,

particularly in the absence of adequate and updated maps. Such a list is also useful for esti

mating the number of enumerators and the number of schedules and other census materials

needed in an area, for estimating the time required for the enumeration and for compiling

provisional results of the census. It is also very useful for determining the enumeration areas

and for establishing necessary links between population and housing censuses when they are

carried out separately. Finally, it can be used as guide to monitor the completeness and quality

of the enumeration of the population in a given area.

3.116. Consideration should be given to providing permanent identiﬁcation to streets and

buildings, which can be used for successive censuses and for other purposes. A listing of sets

of living quarters, particularly in densely settled places, cannot be made unless streets have

names and buildings have unique numbers. Individual apartments in multi-dwelling build

ings need to be numbered or otherwise unambiguously identiﬁed. Where these prerequisites

do not exist, numbering immediately prior to the census would prove useful.

3.117. Where such information is available, it is useful to provide the enumerators with

additional assistance in the form of lists of addresses to visit. Address lists will be essential if

self-enumeration, whereby questionnaires are sent to the households by mail, is part of the

plan. Some countries have population registers that allow more or less complete address lists

to be generated relatively simply. e census can then not only use these lists, but also assist

in further improving the population register by reporting any discrepancies found in the

ﬁeld. Where oﬃcial population registers are not available, or insuﬃciently complete, it may

be possible to obtain additional address lists from postal authorities, utility companies or the

private sector (for example, mail order companies). A deﬁnitive list for the enumerators could

then be prepared by merging the lists obtained from these various sources.

3.118. Where a functioning population register exists, it may be possible to preﬁll the house

hold questionnaires with information such as the names of the persons expected to be mem-

Principles and Recommendations for Population and Housing Censuses, Revision 3100

bers of a household, already available from the register. is reduces the response burden,

accelerates the information-gathering process, and helps to pinpoint deviations. On the other

hand it might have a negative psychological eﬀect if respondents believed that the authorities

were monitoring them too closely. Using one or several registers as the point of departure for

a census that still includes full coverage ﬁeld enumeration is an approach applied in some

countries; diﬀerences between the register(s) and the ﬁeld situation will necessarily come to

light, and rules will be required to deal with such diﬀerences.

VII. Field enumeration

3.119. In recent years, the use of new technologies in conducting censuses has introduced

substantial changes in ﬁeld enumeration. e traditional method of enumerating the popu

lation with face-to-face interviews can be applied in diﬀerent ways, using a paper question-

naire or handheld devices to automatically capture data during enumeration. On the other

hand, self-enumeration methods can also be applied in diﬀerent methods using the Internet.

e use of technology during enumeration would be the main challenge for most coun

tries. It should be noted that only countries that have high penetration rates of information

technology (including the Internet) have implemented Internet data collection, and mainly

in conjunction with more traditional methods. However, these options may never entirely

replace face-to-face enumeration, as even where society enjoys a high degree of information

technology use, the entire population cannot reasonably be expected to comply to a mode

of self-enumeration.

A. Method of enumeration

3.120. ere are two major methods of enumeration. In the face-to-face (or enumerator)

method, information for each individual (in a population census) and for each set of living

quarters and the occupants thereof (in a housing census) is collected and entered in the ques

tionnaire by a census oﬃcial designated to perform this operation in a speciﬁed area. In the

self-enumeration method, the major responsibility for entering the information is given to a

person in the unit being enumerated (usually the reference person of the household), although

the questionnaire may be distributed, collected and checked by a census oﬃcial.

3.121. Traditionally, each household is contacted and enumerated on a face-to-face basis.

is approach is still used in most developing countries and for at least part of the population

in many developed countries. In those circumstances where up-to-date and comprehensive

address or population registers exist or can be established and the level of literacy is high, the

enumeration process often involves mailing out the census forms, or having the public mail

back the completed forms. Where telephone and Internet services have broad coverage, tele-

phone and Internet data collection can also be used. Approaches for self-enumeration using

diﬀerent modes of enumeration, such as mailing, telephone and Internet data collection, may

also be used in combination with the face-to-face method. In some countries, Internet data

collection and postal distribution of the questionnaire, with or without postal return, is used

in conjunction with the self-enumeration method. Both procedures can be used exclusively or

combined with checking by a census oﬃcial. Whatever approach is to be used, the complete

enumeration plan should be prepared well before enumeration begins. is involves (a) the

determination of the enumeration method to be used and the basic procedures to be followed

in the collection of the data and the control of the enumeration; (b) the procedures for the

control of the quality of the data; and (c) an estimation of the number of sets of living quarters

101Census operation activities 101

and the probable size of the population to be enumerated so that the number of question-

naires and other materials required for the enumeration, and the number of enumerators and

supervisors needed, can be properly ascertained.

3.122. Each method has its own advantages and limitations. e face-to-face method is

the only method that can be used in largely illiterate populations or in other population

groups that may be unwilling to complete the census forms themselves or ﬁnd it diﬃcult to

do so. On the other hand, in countries where literacy is virtually universal and educational

attainment relatively high, the self-enumeration method may often yield more reliable results

at substantially lower costs, particularly if Internet data collection or a mail-out/mail-back

procedure can be used. However, postal services may be used to distribute the census forms

only when a comprehensive and up-to-date list of addresses is available or can be prepared.

Another consideration is the emphasis to be placed in the census on obtaining responses,

whenever possible, directly from the person concerned. e self-enumeration method allows

for, and its instructions may encourage, at no extra cost to the census organization, con

sultations among family members when they complete the census form. In contrast, with

the face-to-face method it may be prohibitively expensive to encourage enumerators to go

beyond even the “ﬁrst responsible adult” they encounter in each household. In the light of

these considerations, it may sometimes be desirable to rely on one method for enumerating

most of the population and to use another method in certain areas or for special groups of the

population. With the advance of information technology, the penetration of the Internet has

increased in recent decades. In these circumstances, it is recommended that Internet survey

methodology should be explored depending on national circumstance. is method can be

cost-eﬀective, as the expense of printing questionnaires and wages of ﬁeld staﬀ can be cut

down. Also, self-enumeration through the Internet can secure the privacy of respondents,

so it would be welcomed as more and more people prefer to protect their privacy. However,

a combination of a traditional method and Internet survey can result in duplication during

enumeration. erefore, careful consideration of the management of the dwelling/household

list is essential. Overly complex designs should be avoided and adequate quality checks intro

duced to avoid duplications and frauds.

3.123. e decision regarding the method of enumeration to be employed should be taken

at an early stage on the basis of thorough testing of the various alternatives in terms of their

costs, the quality of the data produced and their operational feasibility. Even where a method

has been followed traditionally, it is well to periodically reassess its relative advantages in light

of current census needs and changing techniques. An early decision is required because the

method of enumeration used aﬀects the budget, the organizational structure, the publicity

plan, the training programme, the design of the questionnaire and, to some extent, the kind

of data that can be collected.

3.124. Challenges that aﬀect or hinder the ability to achieve a response should be fully con

sidered when developing the enumeration design and methods. e design should, as far as

possible, reﬂect particular activities or actions that seek to increase the likelihood of receiving

a response. Challenges can be grouped into two types: people and physical challenges. People

challenges tend to focus on particular subgroups of the population that tend to be diﬃcult

to enumerate for a number of reasons. Physical challenges are ones that relate to the type of

environment in which the people live. e two are not necessarily mutually exclusive.

3.125. e section on groups that are diﬃcult to enumerate (paragraph 4.48) gives a thor

ough overview of the more common population groups that are diﬃcult to enumerate and

how these might be addressed through the enumeration. Other population groups that pose

diﬃculty in enumerating include people with language diﬃculties, nomads, migrants, stu

dents and older persons.

Principles and Recommendations for Population and Housing Censuses, Revision 3102

3.126. People with language diﬃculties. Not all respondents will speak or understand the

language(s) in which the census is being conducted. erefore, consideration and thought

need to be given to translation services and materials, with particular consideration given to

understanding the types and concentrations of languages required.

3.127. Nomads. To successfully carry out the enumeration of nomads, it is particularly nec

essary to pay full attention to preparatory work in order to determine suitable enumeration

techniques. It should be pointed out that there is no absolute methodology for the enumera

tion of nomads, and conditions vary from country to country. e particular method suitable

for a country undertaking to enumerate nomads as part of the census should be determined

only after a detailed preliminary study and after ﬁeld testing. Some of the methods used to

enumerate nomads and semi-nomads may be classiﬁed as follows: (a) group assembly approach,

(b) tribal or hierarchical approach, (c) enumeration area approach, (d) water point approach and

(e) camp approach. Sometimes a combination of two or more methods may be used.

3.128. In the group assembly approach, the nomads are asked to assemble at particular inter

view sites on certain ﬁxed dates. is method can be adopted only through the administra-

tive or tribal authorities. e tribal or hierarchical approach is a favourite method, since the

nomads usually follow what is dictated by the tribal or hierarchical chief. e enumeration

work can be carried out as a kind of administrative census by contacting the tribal chief and

collecting, sometimes from memory and sometimes from a register, all the needed infor

mation on the chief’s followers. e other approach is to contact those followers with the

assistance of the chief or a representative and to collect the necessary data directly from the

household. In this case, the unit of enumeration is not areal but tribal. e enumeration area

approach presupposes creating conventional census enumeration areas and then contacting

each nomadic household that happens to be staying in the enumeration area during the cen

sus. In the water point approach, a list of all water points available to the nomads during the

period of enumeration is prepared. Since numerous temporary water points are created during

the rainy season, a meaningful list of water points may be prepared with reference only to the

dry season. e enumerator is given the task of locating and visiting every nomadic household

that may be using a certain water point. In the camp approach to enumerating nomads, a list

of camps is prepared together with the approximate location of each within the country, and

enumerators are sent to visit all the households in each camp.

3.129. Migrants. Recent migrants to the country may be unfamiliar with the language or

may be unfamiliar with the census and the reasons for collecting the information. erefore,

as part of developing the enumeration design consideration needs to be given to communi

cating with these groups, particularly about the beneﬁts of the census, to ensure that they

understand and are more likely to respond.

3.130. Students. Students can pose a risk to the quality of the enumeration as they tend

to be large in numbers and highly concentrated around universities or other institutions

for post-secondary education. erefore some consideration should be given as to whether

they require slightly diﬀerent, more speciﬁc methods (particularly if they live in large living

quarters) or tailored communication to ensure they understand the beneﬁts of completing a

census questionnaire.

3.131. Older persons. Particular assistance may be required for the population of older per

sons, where literacy rates may be lower, or some of the concepts (such as “age”) are diﬀerent

to what they remember or relate to. For example, depending on the circumstances, additional

materials may be required (such as a calendar of events to help remember or estimate their

age) or speciﬁc activities to provide assistance in completing a questionnaire or interview from

supporters (such as family members, village elders, residential home staﬀ).

103Census operation activities 103

3.132. e more common physical challenges that need to be taken into consideration when

developing methods for ﬁeld enumeration include access-controlled properties and rurality.

3.133. Access-controlled properties. Some properties, establishments, communities or com

pounds have controlled access, presenting diﬃculties in gaining access to undertake an inter-

view or to deliver or follow up on a questionnaire. Access control mechanisms may include

locked gates with an intercom to each individual dwelling, or gates or doors managed by a

concierge or security guards. When developing enumeration procedures, advice needs to be

given as to how to gain access and actions to take if access proves diﬃcult. Some of the activ-

ities may include building a relationship with the owner of the properties to approve access

to engage with residents; using the postal service to deliver questionnaires to these proper

ties; and additional communication methods (such as a letter informing residents about the

census and how to complete their questionnaire or inviting them to arrange a particular time

to complete their questionnaire via interview).

3.134. Rurality. Understanding the extent of rural populations and the associated logistical

and management challenges with running a collection exercise in these areas needs careful

consideration.

B. Timing and length of the enumeration period

3.135. e choice of the time of year in which the census will be taken is of great impor-

tance. e main consideration should be to select a period in which the census is likely to be

most successful and to yield the most useful data. is may depend on a number of factors.

First, it is necessary to avoid those seasons in which it will be diﬃcult to reach all inhabited

areas because of rains, ﬂooding, snow and so forth or in which the work will be particularly

arduous, as is the case during extremely hot weather. Second, a time should be chosen when

most people are staying at their place of usual residence; such a choice will simplify the census

operations both in a de jure and in a de facto enumeration, and it can make the results of a de

facto enumeration more meaningful. Seasons of peak agricultural activity should be avoided

because it is diﬃcult to interview persons who work late every day and who may even stay

nights on their land if the land is far from home. Great traditional festivals, pilgrimages and

fasting periods are also unsuitable times for census work. Since in many developing countries

the bulk of the ﬁeld staﬀ is recruited among schoolteachers and older students, the conduct

of the census may be feasible only during school holidays, though, as already indicated, the

days of major festivals should be avoided.

3.136. In a country that includes areas of sharply contrasting seasonal patterns of weather or

activity or in which potential census personnel are in very short supply, it may be necessary

to enumerate diﬀerent parts of the country at diﬀerent times or to enumerate the nomads

or other special population groups at a diﬀerent time from that established for the settled

population. is, however, is generally not a very desirable solution both because the nomads

cannot always be clearly diﬀerentiated, and because there may be mobility among the settled

inhabitants. Furthermore, such a solution creates complications in respect of the use of the

census data.

3.137. When a census has been taken and the census date is found to have been on the whole

satisfactory, the next census should be taken at the same time of the year, unless there are

strong reasons for changing this date. A regular census date enhances the comparability of

the data and facilitates analysis. e tradition of a ﬁxed census date in a country also pro

vides administrative discipline, motivating all those involved in the census to make necessary

preparations in a timely manner.

Principles and Recommendations for Population and Housing Censuses, Revision 3104

3.138. It is desirable to keep the enumeration period short in order to avoid double counting

and omissions, which can occur in spite of a single reference date. On the other hand, the

shorter the enumeration period, the greater the number of ﬁeld staﬀ that have to be recruited,

trained and supervised. is increases the cost and may lower the quality of the data. How

these diﬀerent considerations should be reconciled depends on the size and nature of the

country and on the resources at its disposal. e length of school holidays is sometimes a

restricting factor, although governments of several developing countries, recognizing the great

national importance of a census, have prolonged the school holidays in the census year in

order to allow teachers and students to work on the census as long as required.

3.139. In recent censuses, most developing countries have allowed about one week to ten

days for the training of enumerators, while the enumeration period has generally varied from

a few days to two weeks. In the case of using a self-response method through the Internet,

the enumeration period can take longer and enumerators may require less training if they are

simply going to follow up on non-respondents. Short periods are often feasible in small coun

tries while longer periods may be necessary in large countries with poor communications.

3.140. One method sometimes used to allow suﬃcient time for enumeration and yet make

the census simultaneous is ﬁrst to enumerate the population over a longer period, say a

week or more, and then, in one single day, to recanvass all households, deleting and adding

persons as needed to update the ﬁles. is procedure is, however, not practicable in very

sparsely settled areas.

C. Management and supervision

3.141. A comprehensive and elaborate management system is necessary for resource manage-

ment and providing timely managerial advice to the ﬁeld staﬀ. ere is no unique approach

for the management system; however, it is important to develop a hierarchical and geographi

cally dispersed system for building a direct and eﬀective communication mechanism between

the managers and the ﬁeld staﬀ.

3.142. Adequate supervision of the enumeration is essential for ensuring the quality of the

ﬁeld enumeration. Many countries use a ﬁeld supervisor/enumerator ratio ranging from 1:10

to 1:15. Periodic control of the quantity and quality of the work accomplished by enumera

tors and other ﬁeld staﬀ is recommended, in order to facilitate the correction of ineﬃciencies

and to maintain satisfactory progress during the enumeration period. Periodic and systematic

assessment should be carefully organized for ensuring the quality of the work and also for

collecting appropriate information about the progress in enumeration for management and

supervision of the ﬁeldwork.

3.143. Each staﬀ member involved in the management and supervision system should have

a clear job description and should be fully trained for possible problems occurring during

ﬁeld enumeration and their solutions. For an eﬃcient system, it is important to give clear

instructions to the ﬁeld staﬀ for performing their own responsibilities. It is important to note

that methods and technologies used during enumeration have a direct impact on the roles

of managers and supervisors; consequently, a complete understanding of the characteristics

and operational aspects of both the enumeration method and the enumeration technology is

a prerequisite for eﬃcient supervision of the enumeration component of the census.

3.144. Depending on the communication facilities and other infrastructure available in a

country, diﬀerent mechanisms for exchanging information among managers and ﬁeld staﬀ

need to be developed. ese mechanisms are important for ensuring consistent dispatch of

ﬁeld instructions and also sharing best practices, particularly for ﬁnding solutions to unex

pected problems during the ﬁeld operation. e use of portable phones and accompanying

technologies, such as SMS, signiﬁcantly increases communication capabilities.

105Census operation activities 105

(a) Management information system

3.145. A management information system for the ﬁeld operation should be established to

collect information needed for timely management and supervision of ﬁeld operations. To

establish this system, the following steps can be considered:

i. Determining information needed for supervising and managing ﬁeldwork;

ii. How and when each piece of information would be collected;

iii. How and by whom each piece of information will be used.

It is important to collect the amount of information that can reasonably be collected

with good quality and used eﬀectively, otherwise every additional topic with low priority will

aﬀect the cost of collecting reliable information.

e following information can be collected through this system:

i. Information about particular activities that are implemented before enu

meration, such as establishment of local census commissions and training

of census ﬁeld staﬀ;

ii. Information about the ﬁeld staﬀ needed for administrative tasks, such as

recruitment and hiring ﬁeld staﬀ, bank account information for payment,

work accomplished;

iii. Progress of enumeration of population and housing units to evaluate if the

ﬁeld operation proceeds according to schedule;

iv. Information about logistics issues, such as shipment of census materials and

questionnaires, timing of receiving and sending materials, and number and

types of materials.

3.146. Census operations can be made more eﬃcient through the availability of a manage

ment information system and use of this system by ﬁeld staﬀ for administrative tasks and

supervision. It is possible to create a quick communication mechanism for key messages and

work allocation. is system should be used for producing and submitting regular reports

providing information about the progress of ﬁeld activities and enumeration. ere are several

ways of collecting such information. Technology-based solutions include the use of SMS,

websites and portals, and mobile or handheld applications.

(b) Supervising the enumeration

3.147. A supervision system to monitor the progress of the operation is important to allow for

correction of errors and to make necessary adjustments in the course of the ﬁeldwork. In coun

tries where the Internet or handheld devices are used in data collection, a computerized online

system can be developed and some automated procedures introduced for the supervision.

3.148. e key to rapid quality control of enumeration is the fast ﬂow of information from

supervisors to the local statistical committees and to the central statistical committee. e

most eﬃcient way of exchanging this information is via the Internet. If local and regional

supervisors have Internet access, information can even be submitted through a password-

protected database interface (a web-based application).

3.149. Close monitoring during the enumeration phase is essential to ensure coverage, quality

and compliance with deadlines. It must be ensured that all staﬀ involved in the data collection

have access to up-to-date reports with relevant information. ese reports should be made

available periodically in printed or digital form. Data from previous census or other sources

can be utilized to improve monitoring and form a database for management indicators.

3.150. As the enumeration is one of the core census processes, each task performed during

the enumeration stage must be carefully planned, executed and supervised to achieve the

Principles and Recommendations for Population and Housing Censuses, Revision 3106

qualitative and quantitative targets. For successful monitoring of ﬁeld enumeration, actual

performance should be evaluated against the set targets. e following are recommended to

achieve the desired outcomes.

i. Using historical data

3.151. Data from previous censuses and other relevant data sources such as household sur

veys and administrative registers should be used as a benchmark to determine the data needed

for monitoring the performance of enumerators. is information can be used for monitoring

actual performance in the enumeration against set goals and targets. Examples of historical

information include total population of previous censuses; population growth rate; sex ratio;

urbanization rate; proportion of vacant dwellings; and occasional use dwellings in relation

to those occupied.

ii. Setting goals and targets

3.152. As a population census is a time-bound project, extension can be considered as failure.

Setting goals and targets will be very important to measure if the series of activities is under

control or not. Goals and targets for measuring the quality of enumeration and for systematic

monitoring of enumeration can be set based on experience of previous censuses and other

relevant data sources. e following indicators can be used for monitoring enumeration:

(a) proportion of occupied and vacant dwellings; (b) average number of residents per dwelling;

deviation between the target values and enumerated values may indicate a problem in the col

lection process. Estimation of housing units and population—if available—based on census

maps and the listing of living quarters and households can also be used as information for

monitoring the enumeration.

iii. Preparing policies and procedures

3.153. Policies and procedures to be used as the baseline for monitoring during enumeration

should be deﬁned at an early stage of the census, with endorsement from the highest levels

of decision-making, for proper management support. erefore, it is important that there is

a stage of evaluation of the previous operation in order to identify gaps and improve control

procedures and execution of work.

D. Use of technology

3.154. Technology is becoming increasingly important for conducting population and hous-

ing censuses. e technological tools and instruments described below are well documented

in national practices in conducting the population and housing censuses in the 2010 round,

covering the period 2005-2014, and as such can be considered in planning for the next round

of censuses, taking into consideration particular conditions of each country.

(a) Electronic questionnaire

3.155. Combined with or completely replacing the paper questionnaire, an electronic ques

tionnaire can be used in either the face-to-face or self-enumeration method. Electronic forms

can provide improved data quality and operational eﬃciencies by implementing validation

rules on individual questions, cross-validation between questions or with other records, auto

matic sequencing (leading the operator to the next appropriate question), more options in pull-

down lists, capturing more detailed data, providing computer-assisted coding and the ability to

ask tailored supplementary questions. Electronic questionnaires can give access to guidelines,

explanatory material and even videos to provide instruction to the interviewer or household.

107Census operation activities 107

3.156. Electronic questionnaires can also provide census results more quickly by transferring

data to a central database immediately or soon after the enumeration, either using real-time

connectivity, or by transferring using physical media to a local centre. Online transmission

should be encrypted and secured for conﬁdentiality purposes. Electronic forms reduce the

amount of material (such as questionnaires) to be printed, distributed and returned, and

reduce data scanning and capture costs and errors. e electronic questionnaire can also

capture a range of operational information that can be used to monitor operations and analyse

responses, including the time taken to complete the form, the date and time the form was

completed and the device used to complete the form.

i. Electronic questionnaire: face-to-face method

3.157. Census interviews can be undertaken using an electronic questionnaire on smart

phones, tablets, laptops or other devices. Each device or enumerator can be linked with the

enumeration area so that the records are tagged with the respective enumeration area to

avoid duplication. e device may also be able to capture information on the location of the

interview, time of day and other metrics that may be useful.

ii. Electronic questionnaire: self-enumeration method

3.158. Achieving a good percentage of enumeration using this method can reduce the opera

tion costs substantially. Electronic questionnaires for households should be implemented in a

secure Internet portal and also in secure documents that are distributed via email. Households

are usually provided with a unique identiﬁer that is used to initiate their questionnaire or

resume a partially complete questionnaire via the Internet. Households may prefer to respond

using an electronic rather than a paper questionnaire for its convenience. If the census is col

lected in a multimodal approach, for example oﬀering both electronic and paper question-

naire options, a system will be required to track the status of each dwelling (questionnaire)

throughout collection to ensure completeness of coverage and ensure non-response follow-up

is not conducted with responding dwellings.

(b) Handheld or mobile devices

3.159. Whether using a mobile device for canvassing or, as is more often the case, for com

munication and supervision of ﬁeldwork, it needs to be determined whether the census agency

will purchase and provide the device, or whether the ﬁeld oﬃcers will use their own devices.

As the availability and proliferation of devices increases, there can be ﬁnancial beneﬁts, as

well as reduced training needs, if ﬁeld oﬃcers can utilize their current device rather than be

provisioned with a new device. Although this does introduce a range of technical, security and

legal considerations, this deployment option has been commonly used with mobile phones

for the last ten years in a number of nations. Another signiﬁcant consideration is the fact that

mobile phones operate on diﬀerent platforms; developing applications that would enhance

communication and monitoring would necessitate developing for diﬀerent platforms and that

increases the costs and eﬀorts.

3.160. Geographic information systems may be used to create digital maps on GPS-enabled

handheld devices, as well as to produce paper maps. For each enumeration area, buildings can

be identiﬁed within the application using GPS coordinates. As the households to be visited

are known, GPS coordinates can be used by a navigation option built for the device to allow

enumerators to reach the household easily. An extensive elaboration on the use of both GIS

and GPS is presented in chapter IV above.

Principles and Recommendations for Population and Housing Censuses, Revision 3108

(d) Contact centre

3.161. e contact centre or call centre is an important element and can be used in each

and every step of the census to support ﬁeld operations. Interactive voice response technol

ogy can be used to address the call to a speciﬁc agent based on the options selected by the

caller, or to resolve the call by providing a common answer. Website call-back and chat can

be implemented to help respondents while ﬁlling the online e-questionnaire in the portal.

(e) Short messaging service (SMS)

3.162. SMS may be used in various stages of the census project to share information with

ﬁeld personnel and respondents. e service may be used to send passwords, guidelines,

alerts, marketing messages, reminders, etc. If the SMS gateway is integrated to the central

database of the census, alerts can be sent to the census management upon various critical

business events and when violation occurs, for example when the monitoring system detects

that “coverage is lower than expected”.

VIII. Data processing

3.163. No matter how thorough and accurate the census enumeration is, the usefulness,

quality and timeliness of the census tabulations will suﬀer unless the collected data are prop

erly processed. An important element of a successful processing operation is the close and

continuing collaboration, at all levels, between the data-processing staﬀ, the subject matter

staﬀ and the general statistical staﬀ. At a minimum, the subject matter and general statisti

cal staﬀ will need to become familiar with and take a continuing interest in the processing

plans and operations, while the processing staﬀ will need to become familiar with and take

a continuing interest in the substantive aspects of the census.

3.164. Plans for data processing should be formulated as an integral part of the overall plan

of the census, and those responsible for the processing of the census should be involved from

the inception of the planning process. Data processing will be required in connection with the

results of census tests, compilation of preliminary results, preparation of tabulations, evalua

tion of census results, analysis of census data, arrangements for storage in and retrieval from

a database, identiﬁcation and correction of errors, and so on. In addition, data-processing

technologies are playing an increasing role in the planning and control of ﬁeld operations and

other aspects of census administration. Data processing has an impact on almost all aspects of

the census operation ranging from the selection of topics and the design of the questionnaire

to the analysis of the ﬁnal results. erefore, data-processing requirements in terms of person

nel skills and knowledge, space, equipment and software (computer programs) need to be

looked at from the point of view of the census as a whole and at an early stage in the planning.

3.165. e existing data-processing staﬀ will certainly need to be expanded and will probably

need some upgrading in terms of skills, particularly if new computer hardware or software

is to be used in the census. Any training that is required should be completed early enough

so that those beneﬁting from the training can play an active role in census planning and

operations.

3.166. Decisions will need to be made concerning the location of the various data-processing

activities within the country, including the extent to which the processing work is to be decen

tralized. is decision should be partly based on the ability to recruit the required personnel

for the processing operations. Acquisition of both equipment and supplies can require long

lead times; estimates of both data capture and computer processing workloads must be made

109Census operation activities 109

early to enable timely procurement. Closely related to the question of equipment is that of

the provision of adequate space. Although the maintenance of most personal computer equip

ment no longer requires adherence to rigid standards in terms of temperature, humidity, dust

and so on, attention to issues related to power supplies is still important. Inevitably, more

important is the attention to be devoted to the maintenance of servers (especially heavy duty

servers), where most of the information is likely to be processed and saved, as well as the data

transmission infrastructure. e last issue is essential to ensure smooth and noiseless Internet

and web communications between diﬀerent units and centres engaged in census operations.

Moreover, in the case of traditional archiving, a well-protected space for the storage of the

completed census forms before, during and after processing will have to be secured.

3.167. In addition to considering the hardware, decisions will have to be made on the soft

ware to be used in editing and tabulating the census data. Several portable software packages

are available for census editing or tabulation. Commercial personal computer spreadsheets,

databases or tabulation packages are also available. Every country should assess its software

requirements in the light of its own needs and resources. Regardless of the software used,

suﬃcient time will have to be allowed for customization of the software and training staﬀ

in its use.

3.168. Outsourcing some of the predominantly IT-related operations may be considered.

Outsourcing should be implemented in such a way as to bring immediate economic and

quality advantages to census operations. Furthermore, national statistical oﬃces should take

adequate measures to ensure that outsourcing of census operations does not compromise data

conﬁdentiality and that necessary steps are taken so that the contractor does not have free

access to the basic census databases. It is worth mentioning that responsibility for hosting

of census databases rests with the national statistical oﬃces and that outsourcing of these

activities is not recommended. In short, outsourcing should be implemented so as to facilitate

a transfer of knowledge into the census organization and always in such a way that essential

features, such as the privacy of individual respondents and the conﬁdentiality of the data,

are fully protected.

A. Method of processing

3.169. e appropriate method of processing is determined by the circumstances of each

country. Rapid advances in data-processing technology have greatly increased the speed and

reliability of producing detailed tabulation, thereby making computer processing the stand

ard method of processing around the world. Furthermore, an alternative to mainframes,

whose computational power was necessary before the advent of lighter and more scalable IT

hardware solutions, is the use of a client-server environment. Several lighter tasks, including

editing and tabulation of data ﬁles, can very well be done on small-sized desktop systems

that can be placed in substantive departments and in ﬁeld oﬃces. On the server side, most

of the heavier computing operations, such as scanning, aggregation and analysis of large sets

of microdata, coordination of data transmission, Intranet web hosting and so forth, can be

executed more reliably than on microcomputers. However, a client-server environment to

handle census data must operate over a robust and secure local area network (LAN) or wide

area network (WAN). erefore, computer work is not necessarily dependent on a centralized

data-processing facility, provided that a robust LAN or WAN interconnects workstations

dispersed over various oﬃces, buildings and diﬀerent parts of the country.

3.170. In a census oﬃce that utilizes a networked computer environment, the central ﬁle

or database servers allow both data and programme ﬁles to be stored in a central location.

is system economizes speciﬁcations of client computers and removes the need for much

Principles and Recommendations for Population and Housing Censuses, Revision 3110

physical movement of programs and data on other computer media. Data storage requires

frequent backups of system information to avoid major data loss due to hardware or software

faults. us, servers have a strategic importance, and their location and administration must

be well-deﬁned and secure enough to ensure data protection. Also, it is recommended that

proper business continuity and security policies duly certiﬁed by the competent authorities

should be in place.

3.171. In determining the type of equipment to be employed and the advisability of a new

machine installation (either complete or partial), or of additions or upgrades to existing equip

ment, consideration should be given to all the processing requirements of the data collection

programme for which the population and housing census is but one part. Only on this basis

can a reasonable decision be made. Decisions on the type of data-recording equipment and

computer equipment should be made at least one year in advance of the scheduled date of

enumeration in order to allow appropriate questionnaire design and proper preparation of

instructions to enumerators, development of coding schemes, speciﬁcation of data-handling

controls and procedures, and recruitment and training of data processing personnel. Rapid

processing of a pretest or pilot census that covers end-to-end census operation, including enu

meration, initial census result, output dissemination, and handing over and closure proced-

ures, is particularly important for identifying improvements needed in the census question

naire, instructions to enumerators, computer systems or whatever other preparations may be

needed. It is recommended, therefore, that arrangements for using appropriate equipment

and software be made well in advance of such tests. It is also recommended that all systems

used to support census operation be thoroughly tested in advance of operations to ensure that

they function as intended and that they are secure (that is, they will not lead to loss of data).

B. Preparation for data capture

3.172. In the case of paper questionnaires, the most common procedure is to have the census

documents arrive in the processing centre in batches by enumeration area. Maintenance of

these batches throughout the data processing is recommended, since documents for a given

enumeration area reﬂect the work of one enumerator and may contain a series of errors typical

of that person. To ensure the integrity of the batches, the census documents should be stored

in a specially designed census document storage facility. e batch for each enumeration area

should ﬁrst be checked for completeness, geographic identiﬁcation codes and other character

istics of acceptability before being sent to the next stage of data processing. Transcribing all

coded data onto another sheet (for example, the coding form) should be avoided since it may

add transcription errors. e same considerations apply to the case of electronic transmis

sion of questionnaires or when the ﬁrst phase of data processing consists of the scanning and

text or image recognition of census questionnaires. In the case of questionnaires transmitted

electronically (self-enumeration on the Internet or using e-forms), it is appropriate to set up a

metadata model where the enumeration area can be recorded. As far as storage is concerned,

if paper questionnaires are scanned, secure media for their backup, not only the originals in

paper, should be planned for.

3.173. If the census is conducted in a multimodal approach, for example using self-response

by Internet and ﬁeld follow-up of non-respondents, it will not be possible to batch question

naires by enumeration area for processing. A master control system will be required to track

the status of each dwelling (questionnaire) throughout collection and processing operations

and ensure completeness of coverage.

111Census operation activities 111

C. Data capture

3.174. Converting the information obtained in the census using paper questionnaires to a

format that can be interpreted by a computer is called data capture. It is possible that several

simultaneous and diﬀerent methods for data capture are being used in a census. ey include

keyboard data entry, (including collection by Internet or using handheld or laptop comput

ers), optical mark reading, optical character reading and image-processing techniques, such

as intelligent character recognition. Computer-assisted keyboard data entry is usually carried

out using personal computer data entry programs with built-in logic controls. Some of the

tasks accomplished by the programs are (a) verifying that enumeration area codes are valid,

and copying them automatically from one record to the next; (b) assigning a number to each

person in a household automatically (and perhaps to each household within an enumeration

area); (c) switching record types automatically if the program’s logic requires it; (d) checking

that variable values are always within predetermined ranges; (e) skipping ﬁelds if the logic

indicates doing so; (f ) supporting keyboard veriﬁcation of the information entered earlier;

and (g) generating summary statistics for the operator and the batch. In order not to delay the

data capture task, data entry applications should limit checking to problems that are either

very serious (for example, wrong enumeration area code), or likely to be caused by a simple

misread or key entry mistake. More sophisticated checking is deferred until the editing stage.

3.175. Optical mark reading (often called optical mark recognition) equipment has been avail

able for many years and has nowadays reached good levels of reliability. Optical mark reading

is the simplest of the commonly available form data capture technologies. Owing to relatively

stringent requirements for the successful data capture of the paper, countries with very dusty

or humid climates and poor transport infrastructures are discouraged from using optical mark

reading. It is necessary to heed special questionnaire design restrictions and consider the quality

of the paper, and adhere to precise speciﬁcations regarding the printing and cutting of the sheets.

In some developing countries, this may mean that local production of the questionnaires will

be problematic. e need to reserve a relatively large space for marking areas and to adhere to

other limitations imposed by optical mark reading equipment sometimes make it diﬃcult to

design the best questionnaire from the point of view of the enumeration process.

3.176. Optical mark reading questionnaires can be marked by the respondent or by the

enumerator. Marking by respondents is attractive from a cost perspective, but it depends on

the presence of a cooperative spirit and relatively universal literacy. A practical problem is

that most optical mark reading devices put restrictions on the writing instrument and the

colours that can be used in the marking. Assuming the rules are followed, the rejection rate

for marked forms is often low, especially if the forms have been inspected visually before

being fed into the readers. Converting a manually completed census questionnaire to optical

mark reading format after it has been received in the census oﬃce is ineﬃcient and becomes

a source of errors, and should therefore be avoided.

3.177. Optical character reading (also called optical character recognition) and intelligent

character recognition consist of the use of special equipment to read characters at speciﬁc loca

tions in the questionnaire. ese two terms identify very similar technological approaches.

Specialized sources tend to identify with optical character reading the capability of recog

nizing printed characters only, whereas intelligent character recognition would extend this

capability to handwritten text. ere is no agreed deﬁnition of intelligent character recogni

tion. In the context of censuses, therefore, this would require that handwritten text in the

ﬁlled-in questionnaire be as standard as possible so as to enable eﬃcient recognition. In gen

eral, recognition of numerals is more eﬃcient in an uncontrolled environment, that is to say,

where the machine has not been adapted to the writing style of a particular person. Optical

character reading and intelligent character recognition technology has matured considerable

with sophisticated recognition algorithms and the use of neural networks for self-learning.

Principles and Recommendations for Population and Housing Censuses, Revision 3112

3.178. Imaging techniques and scanner devices, together with optical character reading and

intelligent character recognition software, have been used by several countries for data cap

ture. Experience shows that signiﬁcantly low error rates are achieved at an optimum cost

using these techniques. e eﬃciency is greater in the case of numerical and alphanumerical

characters written by trained enumerators. However, alphanumerical characters are prone

to higher error rates. Extensive testing must be conducted well in advance to determine the

best type of equipment and paper. e use of imaging techniques is also dependent on the

availability of local maintenance and support capabilities. Whatever methods of coding and

data capture are chosen, it is essential that they be carefully tested before ﬁnal adoption.

Recognition engines can be customized to recognize various sets of characters and scripts,

but unless good experience is available at the census oﬃce, careful planning and preliminary

work are needed in conjunction with the optical character reading or intelligent character

recognition system providers. A combination of intelligent character recognition (for numeri

cal characters) with computer-assisted coding (for alpha characters) is also an eﬀective method

used by some countries.

3.179. In addition to the beneﬁts of the scanning technology for capturing the information,

an important by-product of scanning census questionnaires is that this allows for the possi

bility of digitally ﬁling and naming the scanned questionnaires. is increases the eﬃciency

of storage and retrieval of the questionnaires for future use, particularly during subsequent

data-editing operations.

3.180. e quantity and type of data entry equipment required will depend on the method

of data capture selected, the time available, the size of the country, the degree of decentraliza

tion of the data capture operations, and a number of other factors, such as the use of digital

enumeration approaches. For keyboard data entry, the average input rates usually vary between

5,000 and 10,000 keystrokes per hour. Among the factors that aﬀect operator speed are (a) the

supporting software and program with easily navigable screens, spell checker on the descrip

tion ﬁelds if any, keyboard shortcuts throughout the program, less utilization of the computer

mouse, and so forth; (b) the complexity of the operators’ tasks; (c) the ergonomic characteris

tics, reliability and speed of the equipment; (d) the question of whether work is always avail-

able; (e) the training and aptitude of the recruited staﬀ; and (f ) the motivation of the workers.

3.181. Several options are available to help ensure that data entry operations are completed

in a timely manner. ey include (a) procuring more equipment; (b) increasing the number

of working hours by working double or even triple shifts and during weekends; and (c) apply

ing independent veriﬁcation to varying extents. In the case of keyboard data entry, with the

increasing safeguard of data quality by data entry programs, complete veriﬁcation has become

less necessary. Full independent veriﬁcation may be applied only in the initial stage of data

entry and may be reduced when each worker has achieved an acceptable level of quality.

After that, a sample veriﬁcation plan can be applied. Operators may be assigned to sample

veriﬁcation depending on their observed error rate. e work of reliable operators may be

veriﬁed only for a small sample of the enumeration areas, while more extensive veriﬁcation is

continued for the more error-prone operators.

D. Coding

3.182. Whenever possible, precoded responses should be used in census questionnaires with

numerical or alphanumerical codes. Since computer editing and tabulation of textual material

are not practical, verbal responses will have to be replaced by a code. is can be done by a

dedicated computer program for automatic coding or by a coder (possibly computer assisted)

for situations where answers cannot be automatically coded. ere are obvious advantages to

directly coding the respondent’s answer into the questionnaire during the interview, since the

113Census operation activities 113

respondent is still present to provide clariﬁcations if necessary. Unfortunately, in most cases

this is not practical because enumerators are normally insuﬃciently trained and they cannot

be expected to carry the required codebooks and manuals during census enumeration. In

any of the enumeration methods, the response can be collected as text, and later converted

to proper code by coding experts. Given the size of the coding operations in a census, time

should be spent optimizing the automatic coding operations to reduce human intervention

(see paragraph 3.187).

3.183. Automatic or computer-assisted coding will eﬃciently support the coding activity,

reducing coding errors and speeding up the coding process. When required, a coder normally

works with one or several codebooks for various items in the questionnaires. Coders may spe

cialize in certain variables, with one group of coders handling only geographic references,

another responsible for detailed occupation and industry coding, and so forth. In any event, this

is tedious work and can be a major source of errors. To avoid new sources of errors, coders should

not rely only on their memory; they must base their function on the use of the codebooks.

3.184. Computer-assisted coding uses personal computers to assist the coders. e process

requires that all the codes be stored in a database ﬁle and be accessed by coders during the

coding operation. Computer-assisted coding is based on at least two general approaches. In the

ﬁrst one, coded answers are matched to a set of keywords. Textual information from the census

questionnaire is parsed and compared to an indexed list of keywords, and then the likelihood

of matching between found keywords and coded answers is measured and scored. If the score

results are over a certain (high) threshold and there is no ambiguity, a sorted list of coded

answers is presented to the coder, who retains the ultimate decision of accepting or refusing

the system’s proposed answers. In using this method, it may be advantageous to change the

order of activities so that the capture of precoded information in the questionnaire occurs ﬁrst,

followed by the capture and computer-assisted coding of the remaining information.

3.185. In the second approach, which is mainly used in image processing of data (intelligent

character recognition method) for non-Latin or multilingual countries, owing to the diﬃ

culty and existing problems in character (alphanumerical string) recognition, the procedure

is as follows. After the scanning and during the coding operation phase, the image of the

text will be shown on the monitor, and at the same time, a pull-down menu from a coding

database will present the coder with the ability to enter as few key entries as possible to get to

the full textual and coding content of a speciﬁc case. When the coder selects a code, it will

be allocated and saved in the database for that speciﬁc case. Although this approach is more

time consuming and costly in comparison to the ﬁrst approach, the quality of coding is much

higher than in the traditional way of coding.

3.186. On the other hand, both techniques have several similar advantages: (a) capturing the

precoded information at an early stage leads to some data ﬁles becoming rapidly available,

which opens up the possibility of generating and releasing preliminary census results; (b) the

computer-assisted coding process provides an opportunity for a computer system to alert the

operator to problems with data supposedly already captured, for example, missing information

for a fully precoded variable; (c) the coder works directly on the computer screen; and (d) infor

mation from other variables may be helpful in determining applicable codes for write-ins.

3.187. Automatic coding is a process in which the decision about the code to be assigned is

delegated to a computer program. e main diﬀerence from computer-assisted coding consists

in the automatic acceptance of the answer if its score is over a predetermined threshold and

relatively higher than possible identiﬁed alternatives. Both computer-assisted and automatic

coding systems may exploit self-learning capabilities of neural networks to ﬁne-tune their

capacity of detection. A human operator becomes involved only in those cases where the soft

ware cannot resolve the issue. Computer coding may use, in addition to the written response

Principles and Recommendations for Population and Housing Censuses, Revision 3114

for the item in question, other relevant information available in the record or the questionnaire.

erefore automatic coding is more applicable in cases where the data-capturing process has

already been completed, by Internet, handheld devices or other forms of electronic data col

lection, manually or by some form of automatic reading. Developing computer software for

automatic coding is a complex task. Automatic coding methods need to be complemented by

computer-assisted or conventional coding methods for unresolved responses.

E. Data editing

3.188. Raw data ﬁles contain errors of many kinds, some generated by respondents and oth-

ers caused by enumerators who misunderstood the respondents’ answers. Further mistakes

are introduced in the data-processing operations and during coding and data entry, or in the

course of the transcriptions that take place. From an operational point of view, such errors are

of two types: (a) those that have the potential of blocking further processing (critical errors);

and (b) those that introduce distortions into census results without interrupting the logical

ﬂow of subsequent processing operations (non-critical errors). All of the ﬁrst type of errors and

as many as possible of the second type must be corrected. Prior to error correction operations

and in case there is a need to go back over work, precautionary action should always be taken

by following proper management procedures and versioning the changes with a backup copy

of the original data ﬁle at every stage.

3.189. Since for large censuses manual correction is rarely economically feasible, the con

ditions for such corrections are usually speciﬁed in specially designed computer programs

for automatic error scrutiny and imputation based on other information for the person or

household or for other persons or households. Whenever imputation is used, a ﬂag should be

set so that analysts are able to distinguish between reported information and that imputed

by the editing system. For cases where suﬃcient information is unavailable for the speciﬁc

persons or household to correct apparent errors, imputation methods can be used such as the

hot deck approach. is technique uses information obtained from previously processed per

sons, families or households with similar characteristics as the “best suited” value in replacing

missing values or values that have failed processing edits. However, this technique requires

careful programming work, considering that the search for appropriate information in the

census database would slow down computer program execution.

3.190. In some cases, the best solution will be to move out-of-range or clearly inconsistent

values into a special category, prior to deciding how such cases should be edited and classi

ﬁed. In this way, the pitfalls of introducing statistical biases are considerably reduced. But

precautionary measures should also be deﬁned and set for the fact that overambitious auto

matic editing programs may cause the so-called “corrected” data to be signiﬁcantly ﬂawed.

In this respect, it would make sense to have an acceptable cut-oﬀ value for error rates at the

enumeration area level. If a data scrutiny program ﬁnds that more than a certain percentage

of the records in a particular batch have one or more serious problems, the whole batch should

be rejected and subjected to human or ﬁeldwork veriﬁcation.

3.191. Editing and imputation rules should be formulated by subject matter specialists, not

by computer programmers; also, an error scrutiny and editing plan should be elaborated at

an early stage of the census. A set of consistency rules and corrective measures should be

put in writing and made available to the programming staﬀ, leaving no room for confusion,

misinterpretation or unwarranted independent initiative. e computer programmers should

implement these editing rules by working as a part of a team with the subject matter special

ists. e programs should be tested by subject matter experts and software testing experts for

various scenarios before using them with the census data set.

For further details on census data

editing, see Handbook on Popu-

lation and Housing Census Editing,

Revision 1, (UnitedNations publi-

cation, Sales No. E.09.XVII.11).

115Census operation activities 115

F. Validation

3.192. e outcome of editing is a set of records that are internally consistent and in which

person records relate logically to other person records within the same household. is process

does not, however, provide the full range of assurance necessary to accept the data set as the

best possible. A range of conditions could cause errors that cause the data to be consistently

wrong: for example, perhaps a condition in the editing suite itself is set incorrectly; propor

tions in an imputation program may be miscalibrated; or enumerators may complete a col-

lection control panel incorrectly. To identify such consistent errors it is necessary to critically

review some key aggregate tables to isolate outlier aggregates and identify the cause of the

unusual values. ese key tables may be a subset of those intended for output or may be tables

speciﬁcally designed for this purpose.

3.193. It is recommended that a bottom-up approach be used in this process. at is, the

tables should ﬁrst be examined for a selection of enumeration areas, then the next level up

and so on up to the ﬁrst set of national tables. ere are two reasons for this:

(a) e ﬁrst enumeration area will complete the processing cycle well before any

other geographic level. us, commencing at this level gives the earliest possible

warning of a problem, enabling corrections to be made before a large amount of

reprocessing is required.

(b) It is far simpler to examine a few hundred records within an enumeration area

than to attempt to resolve the problem in the millions of records in a national ﬁle.

3.194. A crucial stage in the process is designing the analytical tables. One way of approach

ing this could be to identify a set of variables that are conceptually consistent with those in

the previous census (or a major survey) or administrative records from various authorities in

the country, such as expatriate visas issued, national ID programme or number of registered

establishments. us a set of benchmark values could be constructed before the census opera

tion commences and compared with those from the current enumeration. e content of the

benchmark set will depend upon the content of the enumeration, and much of this must

therefore be determined by each country. However, any census will include the variables age

and sex, so a comparison of the age pyramid and sex ratio for each ten-year age cohort would

be basic elements of such analysis.

3.195. A second component of the analysis is the compilation of a set of information regard

ing expected changes since the benchmark survey. For example:

(a) It is possible that in the time since the previous collection improvements in mater

nal health care programmes have led to an increased survival rate for women.

us intercensal cohort survival ratios for females should be higher for younger

women than older ones.

(b) If literacy is included in the analysis, and government policy has been to strongly

support increased school attendance, an increase in the proportion of literate

people could be expected.

3.196. ere will be a need for careful judgement when the analytical tables show a signiﬁ

cant and unexpected diﬀerence from the benchmarks. While it may be found that the dif-

ference is due to a problem with the current collection, it could also be due to:

(a) A problem in the collection that has generated the benchmarks;

(b) A genuine and previously undetected social change that is being correctly revealed

by the current collection.

3.197. In the latter two cases it would be wrong to make any change to the current data set.

However, it is crucial that details of the investigation are made known to users (by preparing

suitable metadata) so that they would be able to treat and analyse the data correctly. If the

Principles and Recommendations for Population and Housing Censuses, Revision 3116

analysis indicates that there is a problem with the current collection, it will also be a matter

for judgement on how to react to it. One proposition is to revise the input processing system

in order to prevent the problem from being perpetuated. After applying such changes, and

in order to avoid introducing further problems, it is essential that they be fully tested and

accepted. e second proposition is to make a decision as to whether or not to reprocess the

records that have already been processed. is decision should be guided by the following:

(a) Signiﬁcance of the error;

(b) Number of questionnaires that have already been processed;

(d) Impact of such a decision on other consecutive phases of the census (such as

tabulation and dissemination);

(e) Cost and expenditure of that decision.

G. Processing control

3.198. Careful planning and control are required to ensure an uninterrupted ﬂow of work

through the various stages from receipt of the census questionnaires through preparation of

the database and ﬁnal tabulations. e plan should provide for the computer edit to follow

closely the coding, checking and recording of the data so that errors can be detected while

knowledge related to them is fresh, and appropriate remedial actions may be taken.

3.199. Countries may wish to establish a computer-based processing management and con

trol system to check individual forms or groups of forms for each enumeration area or for

other processing units. Such a system should link the databases for enumeration areas and

other geographic entities with the control information. e system would check and manage

progress from process to process so as to ensure the completeness of records at each stage of

the processing operations. As speciﬁed earlier, project management software may support the

formal description of diﬀerent processes and provide an environment to control the execu

tion of all operations connected to an individual phase or status of the census. is system

should be fed into the overall quality assurance and improvement system, the management

of which is elaborated in paragraphs 2.192-2.200. If a computer-based processing system is

established, a close and real-time communication between the headquarters, local oﬃces

and ﬁeld enumerators should also be established. is is beneﬁcial to the control of ﬁeld staﬀ

and the management of logistics of enumeration materials. Also, as any problem occurs in

the enumeration ﬁeld, this solution can be shared through the bulletin board in the system,

which can greatly reduce non-sampling error.

H. Master ﬁle

3.200. When data editing is in progress, new ﬁles consisting of clean data records for each

person are produced; these can be assembled so as to build a master ﬁle for later tabulations

(often called the microdata ﬁle). is master ﬁle, like the raw data ﬁles, can have a simple

rectangular sequential format. ere is usually no need for having the master ﬁle organized

with a database structure with index ﬁles (but neither should it be discouraged). However,

the master ﬁle should usually be maintained in geographic order, starting with the lowest

geographic entity, sorted by housing unit, household or family. Another method commonly

used to generate tabulations involving both the individual and the family, household or hous

ing unit is to include in the head of household’s record selected characteristics of these latter

units. Alternatively, a single hierarchical ﬁle can be created involving, for example, person,

117Census operation activities 117

family and housing unit records. Whatever the chosen structure, the master ﬁle must allow

for easy checks, controls and computations to be performed.

3.201. One of the most common and problematic errors in census ﬁles is that diﬀerent enu

meration areas carry, for one reason or another, the same identiﬁcation codes. Upon sorting

the ﬁle, these enumeration areas may have been merged, generating households with abnor

mal characteristics such as two heads of household, twice the usual number of members, two

housing records, and so on. To avoid this problem, the enumeration area geocodes should be

checked carefully prior to the editing phase. is is best done by keeping a check ﬁle of all

expected code combinations, and marking a code as “used” once an enumeration area using the

code has been processed. A module of this functionality can be part of the editing programme.

e check ﬁle will serve to ﬂag impossible or double identiﬁcation codes, and towards the end

will show which enumeration areas were expected but have not been processed.

3.202. Census master data ﬁles are usually very large and require powerful servers to process.

Well-equipped desktop systems have higher computational power and are equipped with

much bigger and cheaper mass storage devices than in the past. Nonetheless, the hardware

infrastructure available to several countries is older, thus two strategies are applied to reduce

ﬁle size and to make data management simpler. e ﬁrst involves working with the next

lowest geographic entity as a basis, processing the data on this level and aggregating later to

obtain national results. e second remedy is to apply on-the-ﬂy compression and decompres

sion to the storage medium. Census ﬁles can be compressed quite signiﬁcantly to less than

20 per cent of their original size. Since tabulation programs access the data in sequential order,

using the compressed data will result in a faster reading process.

I. Methods of tabulation

3.203. Preparing the tabulation plan is the substantive responsibility of the demographers

and other subject-matter specialists who have the necessary expertise in interpreting the

census results. is will require consultation with principal users of the census information

(see paragraphs 2.98-2.113). e duties of the data-processing department should be limited

to checking the logic of the various accumulations, designing the required programs and

producing correct results within the shortest possible time. It is possible that the need for

initially unforeseen tables will become apparent, so the census organization should always be

prepared to produce additional aggregations. is may involve newly deﬁned classes for cer

tain variables, new types of cross-classiﬁcations, diﬀerently deﬁned geographic subdivisions,

and so on. If the master ﬁle is organized according to the principles of relational databases

in a relational database management system, original and additional aggregations can be

designed according to relatively easy structured query language statements. In the case of a

list of records with a rectangular structure, online analytical processing tools might be used

to generate multidimensional tabulations. However, if the information needed to produce

these aggregations is not available in the master ﬁle, it will usually be prohibitively expensive

to attempt to add this information at a later date.

3.204. e use of software packages speciﬁcally designed to produce census tabulations is

highly recommended. ese packages will make the job of preparing a useful program much

simpler (and thereby help prevent errors). Usually designed for maximum execution speed

(given that large ﬁles are to be processed), these systems are often available free of cost, or

for just a nominal fee.

3.205. Tabulation work can also be easily done by software belonging to either of two other

classes: statistical analysis and database software. However, these packages have not been

designed with large-scale sequential or geographic processing in mind. ey may require

Principles and Recommendations for Population and Housing Censuses, Revision 3118

substantially more computer time than a specialized census tabulation system. In countries

with a limited capacity of powerful computers, this can be an important consideration.

3.206. Other factors that should be taken into consideration when selecting software pack

ages for tabulation work include:

(a) e availability of expertise in the census oﬃce. It makes no sense to switch to a

software system that is only marginally better when this would require a major

retraining eﬀort;

(b) e need for customization of the software to perform advanced functions, such

as random perturbation to preserve conﬁdentiality.

Moving to a diﬀerent software environment should be the result of a careful analysis

of all the factors concerned.

IX. Evaluation of the results

3. 207. A census evaluation programme should be developed as part of the overall census

programme and integrated with other census activities. e scope and objectives of the evalu

ation programme should be decided well in advance to determine early enough the adequate

resources (both ﬁnancial and human) needed for the evaluation programme. It is important

to establish a team responsible for the planning, organization and implementation of the

evaluation programme. e cost of evaluation should be covered in the census budget as a

separate item.

A. Purpose of census evaluation

3.208. e quality of population and housing census data is very important for many rea-

sons, including building public trust in and understanding of the national statistical system.

e purpose of census evaluation is to provide users with an acceptable level of accuracy and

conﬁdence when utilizing the data, and to explain errors in the census result. It is therefore

important to choose an appropriate way of sending out these messages to the right group of

stakeholders.

3.209. e evaluation methods discussed here are those that apply to traditional censuses.

To some extent they also apply to register-based censuses and other census methodologies,

but these also present their own particular challenges and solutions.

3.210. It is universally accepted that a population census is not perfect, and that errors can

and do occur at all stages of the census operation, but these errors should be measured. Errors

in the census results are classiﬁed into two general categories—coverage errors and content

errors. Coverage errors are the errors that arise due to omissions or duplications of any of the

enumeration units—persons, households or housing units—in the census enumeration. e

sources of coverage error include incomplete or inaccurate maps or lists of enumeration areas,

failure on the part of enumerators to canvass all the units in their assignment areas, duplicate

counting for persons who have two or more places of residence, persons who for one reason or

another do not allow themselves to be enumerated, erroneous treatment of certain categories

of persons such as visitors or non-resident aliens, and loss or destruction of census records after

enumeration. Content errors are errors that arise from incorrect reporting or recording of the

characteristics of persons, households and housing units enumerated in the census. Content

errors may be caused by several factors, including poorly phrased questions or instructions,

See, for example, UNECE

Secretariat for the Eleventh

Joint UNECE/Eurostat Meeting

on Population and Housing

Censuses, Census Quality

Evaluation: Considerations from

an International Perspective,

Geneva, 13-15 May 2008,

available from www.unece

.org/stats/documents/2008.05

.census.html.

119Census operation activities 119

or enumerator errors in phrasing the census questions; inability or misunderstanding on the

part of respondents in respect of answering speciﬁc items; deliberate misreporting; errors due

to proxy response; and coding or data entry mistakes.

3.211. Many countries have recognized the need to evaluate the overall quality of their

census results and have employed various methods for evaluating census coverage as well

as certain types of content error. Comprehensive evaluation should also include assessment

of the success of census operations, in each of its phases, including evaluation of activities

such as the census publicity campaign, data collection, data processing, data dissemination

and data utilization. Countries should ensure, therefore, that their overall census evaluation

eﬀort addresses the census process, as well as the results. e present section is devoted to

evaluation of the results. However, the section on the quality assurance and improvement

programme (paragraphs 2.171-2.228) provides further recommendations relating to control

ling and assessing the quality of census operations.

3.212. Evaluation eﬀorts focused on census results should generally be designed to serve the

following objectives: ﬁrst, to provide users with some measures of the quality of census data to

help them interpret the results; second, to identify as far as is practicable the types and sources

of error in order to assist the planning of future censuses; and third, to serve as a basis for con

structing a best estimate of census aggregates, such as the total population, or to provide census

results adjusted to take into account identiﬁed errors at national or subnational levels if some

errors such as coverage error are substantial and the validity of census results is questionable.

3.213. As the decision to adjust census ﬁgures is sensitive, it is bound to be decided at the

highest levels of the government bureaucracy. ere is also some critical statistical consid

eration that should be very carefully weighed in. Consideration must be given to what geo-

graphic domains the adjustment would cover, knowing that such adjustments have an eﬀect

on demographic distributions.

3.214. e ﬁnal publication of census results should include an estimate of coverage error,

together with a full indication of the methods used for evaluating the completeness of the

data. e publication should also provide users with some cautions or important notes about

the results, in addition to some guidance on how they might use the evaluation results. It is

also desirable to provide, as far as possible, an evaluation of the quality of the information on

each topic and of the eﬀects of the editing and imputation procedures used.

3.215. e range and quality of editing in regard to the correction of the inconsistent data

and imputation possible in a population census are greatly enhanced by the use of computer

editing programs that permit inter-record checks (for example, the replacement of missing

values based on one or more items on the basis of reported information for other persons or

items). If any imputation is made, the topics aﬀected, the methods used and the number of

cases aﬀected should be documented and clearly described in the census evaluation report.

3.216. e results of the evaluation of census results should be made available to users with

a measure of the quality to help them interpret the results.

3. 217. As discussed in the following subsection, a number of methods exist for carrying out

a census evaluation. In practice, many countries use a combination of such methods in order

to fully serve these objectives.

B. Methods of census evaluation

3.218. e choice of evaluation methods to be used depends upon the evaluation objectives.

ese, in turn, depend on national census experience in terms of past and anticipated errors,

user and public concerns, and the ﬁnancial and technical resources available for evalua

Principles and Recommendations for Population and Housing Censuses, Revision 3120

tion. e decision needs to be made whether to measure coverage error, content error or a

combination of the two. In addition, both gross and net error must be taken into account in

developing the overall evaluation plan. Gross coverage error in a census is deﬁned as the total

of all persons omitted, duplicated or erroneously enumerated. Net coverage error takes into

account the underestimates due to omissions and the overestimates due to duplications and

erroneous inclusions. When omissions exceed the sum of duplications and erroneous inclu

sions, as is usually the case in most countries, a net undercount is said to exist; otherwise, a

net overcount results. Similarly, both gross and net content errors have to be considered in

the evaluation design.

3.219. Numerous methods are available to estimate the coverage and content error of cen

suses. ese include simple techniques of quality assurance, such as internal consistency

checks. Comparisons of results with other data sources, including previous censuses, current

household surveys and administrative records, are also useful techniques. Such comparisons

may be made in aggregate by comparing the overall estimates from two sources (net error

only). Alternatively, record checking, whereby individual census records are matched against

alternative sources and speciﬁc items of information are checked for accuracy, may be used.

Both gross and net errors can be estimated in record checks, which may involve ﬁeld reconcili

ation of diﬀerences, a costly exercise that cannot be overlooked. An important but complicat-

ing factor in the use of record checks is the requirement of accurate matching. It is essential

to plan carefully for this aspect, since the operation can be tedious and costly. It should be

noted that record checks are best employed to study the coverage of certain segments of a

population, such as children whose birth records are complete, since these checks are, by

deﬁnition, limited to subpopulations with complete, accurate records.

3.220. Demographic analysis and post-enumeration surveys

are two very important meth-

ods for evaluating census data, and these are discussed in further detail in the following two

subsections.

C. Post-enumeration survey

3.221. e post-enumeration survey can be deﬁned as the complete re-enumeration of a rep-

resentative sample of the census population and matching each individual who is enumerated

in the post-enumeration survey with information from the main enumeration. e objectives

of the post-enumeration survey can be summed up as follows:

(a) To assess the degree of coverage during census enumeration;

(b) To examine the impacts of coverage deﬁciencies, if any, on the usefulness of the

census data;

(d) To examine the characteristics of persons who may have been missed during

census enumeration.

3.222. While a post-enumeration survey can be designed to provide a comprehensive evalu

ation of coverage and content error, especially when supplemented by and integrated with

detailed demographic analysis of census quality, the methodology of a sound post-enumer

ation survey is complex, so that countries must accordingly weigh with care the demanding

technical requirements and the costs of conducting a successful post-enumeration survey,

and elaborate a clear statement of its objectives, before deciding to undertake such a survey.

Careful advance planning is crucial. To be valid, a post-enumeration survey has to function

within a number of operational and statistical constraints. ese include the requirement

that the survey be carried out within a few months of the end of the census to ensure that the

Note that for the purposes of this

publication, a post-enumeration

survey is deﬁned as being a post-

census evaluation survey.

An elaboration of technical

issues is provided in

UnitedNations Statistics Division

Post Enumeration Surveys:

Operational Guidelines, Technical

Report (2010), available from

https://unstats.un.org/unsd

/demographic/standmeth

/handbooks/Manual_PESen.pdf.

121Census operation activities 121

impact of natural population changes (births, deaths and migration) and lapses in respondent

recall do not hopelessly complicate the exercise.

3.223. Another basic property of post-enumeration survey design and execution involves

matching and reconciliation. Matching the post-enumeration survey person record or house

hold record against the corresponding census record is an operation whose performance must

be of very high quality to ensure that inaccuracies in the post-enumeration survey itself do

not eﬀectively ruin the estimate of coverage error. Matching is especially diﬃcult in countries

where many surnames are identical or where individuals are known under more than one

name, and well-deﬁned street addresses do not exist. Part of the matching operation usually

involves a ﬁeld visit to reconcile diﬀerences between the census and the post-enumeration sur

vey with regard to either coverage or content. Reconciliation of course adds another dimen-

sion of cost and complexity, since it entails a second visit to the ﬁeld for purposes related to

the post-enumeration survey.

3.224. Clearly deﬁning the objectives of a post-enumeration survey is the ﬁrst and most cru

cial step in planning the survey. e objectives might include estimation of coverage error at

the national level; estimation of coverage error for major subnational domains or population

subgroups, each with its own speciﬁed level of precision; and measurement of content error

for speciﬁc census items.

3.225. As mentioned, the design of a post-enumeration survey is complex and there are vari

ous alternatives, primarily depending upon whether single or dual system estimation is to

be utilized. A number of references are available that set out highly detailed procedures for

designing a post-enumeration survey and the conditions under which they may or should be

considered.

However, in general, when designing a post-enumeration survey, the following

considerations should be taken into account:

(a) e time between the census and the post-enumeration survey should be mini

mized to avoid as much recall error as possible and the impact of population

changes (births, deaths and migration).

(b) e post-enumeration survey must be independent of the census. Interviewers

must not have census information about the areas where they are working. When

interviewers have knowledge of census responses, they tend only to conﬁrm what

the census recorded.

and processing operations must be completely separate from the census data col

lection and processing.

3.226. e sample design for a post-enumeration survey must be based upon sound probabil

ity sampling methods taking account of the measurement objectives of the evaluation study.

ese usually include the need to estimate census coverage with a certain degree of reliability.

In addition, estimates of coverage may be desired for geographic areas such as provinces or

states and large cities, for urban-rural comparisons and so forth. Such requirements also greatly

aﬀect the sample design of a post-enumeration survey, as the necessary sample size is increased

substantially when estimates of subnational coverage (or undercoverage) are required.

3. 227. Sometimes a post-census survey is designed to measure content error only, in which

case it is usually known as a reinterview survey. e advantage of a well-designed reinterview

survey is that the results are more accurate than those of the census insofar as the operation is

much smaller and can be more eﬀectively controlled. Estimates of relative response bias can

be obtained from a reinterview survey, which (rather than the census) is generally taken as

the standard in this area on the grounds that the survey, with its better-trained interviewers

and more intensive survey procedures, yields superior results.

United Nations Statistics

Division, Post Enumeration

Surveys: Operational Guidelines

(2010), available from http://

unstats.un.org/unsd

/demographic/standmeth

/handbooks/Manual_PESen.pdf.

Principles and Recommendations for Population and Housing Censuses, Revision 3122

3.228. As part of the design of some post-enumeration surveys, a sample of the original cen-

sus enumeration districts, blocks or areas is chosen and recanvassed for the survey. As regards

methodology, this constitutes a useful reinterview technique for measuring content error,

and such an element in the design is often put into practice because the matching operation

between survey and census records is then dramatically simpliﬁed.

D. Demographic analysis for census evaluation

3.229. Demographic analysis oﬀers a powerful methodology for evaluating the quality of

a census, and countries are encouraged to use it as part of their overall census evaluation

methodology. A wide variety of demographic techniques have been developed and used,

ranging from visual inspection of census data to comparative analysis of two census age

distributions. A basic procedure for assessing census quality on age-sex data is graphical

analysis of the population pyramid. Age heaping, or the tendency of respondents to report

a particular ending digit, is a useful check of the quality of age reporting, as are sex ratios

by age and certain summary indices of age-sex data, including the United Nations age-sex

accuracy index, which extends age-sex ratio analysis by observing deviations of the observed

age-sex ratios from the ones expected for each ﬁve-year age group and combining the results

into a single score.

Other summary indices are Whipple’s index and Myer’s blended index,

used for judging age heaping.

3.230. Stable population theory has also been used in the past to assess the quality of census

distributions by age and sex. It is based upon measuring the reported age-sex distribution

against that of an appropriately chosen stable population, assuming that the population is

not aﬀected by signiﬁcant international migration. However, nowadays there are few coun

tries where the other two conditions assumed under the model, namely constant fertility

and constant or recently declining mortality, are satisﬁed. Recent declines in fertility render

the technique less useful as an evaluation tool, since the technique is sensitive to changes in

fertility levels. Nevertheless, if the population is closed to migration, it can be assumed to

have been stable in the not-too-distant past and if approximate estimates of recent fertility

and mortality declines and recent growth rates are available, it may still be possible to assess

the plausibility of the current age-sex structure in the light of these trends by iteratively ﬁtting

projected population structures to the observed numbers.

3.231. e methods mentioned above, while useful in providing an overall assessment of

census quality, cannot diﬀerentiate the sources of census error in terms of the relative con

tributions from undercoverage (or overcoverage) or content error. Better information about

coverage error, through demographic analysis, derives chieﬂy from comparative analysis of

data from successive censuses, in which four methods are used.

3.232. e four methods are:

(a) Derivation of an expected population estimate taking account of vital registers

of births, deaths and net migrants between censuses, as compared with the latest

census;

(b) Population projections based on the results of the prior census plus data on fertil

ity, mortality and migration from various sources and comparing the projected

estimates with the new census results (cohort component method);

rates; and

(d) Estimates of coverage correction factors using regression methods to make the

age results from the two censuses mutually consistent (cohort survival regression

method).

See Methods of Appraisal

of Quality of Basic Data for

Population Estimates: ManualII

(UnitedNations publication,

Sales No.E.56.XIII.2).

Detailed methodologies includ-

ing step-by-step procedures for

applying all the demographic

techniques mentioned above,

plus others, are contained in

United States Department of

Commerce Bureau of the Census,

Evaluating Censuses of Population

and Housing (Washington, D.C.,

1985).

123Census operation activities 123

It should be noted that the ﬁrst two methods would probably have to be restricted to

evaluation studies of coverage at the national level, especially in countries that do not have

good subnational data on migration.

E. Acceptance of results

3.233. In countries with limited prior census experience and without a well-functioning civil

registration system, where population data are based largely on estimates, it is important to

inform the users, particularly the governmental authorities, that the census results could dif

fer from such estimates and to explain the reasons for these diﬀerences. In some cases, there

may be doubts expressed about the census results; usually those doubts focus narrowly on

the total population of the country, major subdivisions or population subgroups, rather than

on the bulk of the census data relating to characteristics of the population or on the data for

local areas. In this situation, it may be possible to take such doubts into account by modifying

the census evaluation programme or by adding appropriate qualiﬁcations to the text of the

census reports or in tabular footnotes. Nevertheless, the government may proceed with the

processing and dissemination for oﬃcial purposes. In any case, every eﬀort should be made

to process and evaluate the full census and to make appropriate use of as many of the census

tabulations as possible.

X. Census products, data dissemination

and utilization

A. Introduction

3.234. e population and housing census is a statistical operation of exceptional value to

every country. It is the primary source of basic national population data for administration

and for many aspects of economic and social planning. Consequently, data from national

censuses represent a valuable public good that should be widely promoted by national statisti

cal and census oﬃces in order to enhance its utilization by the various users. us, the census

should not be an end in itself but should be backed by the value of the results, in terms of

utilization, and by the diverse categories of data users.

3.235. Timely and quality census data are indispensable for informed decision-making,

development planning and better implementation outcomes. Speciﬁcally, census data are

instrumental in understanding development challenges and the appropriate actions for inﬂu

encing and informing change in relation to socioeconomic progress and environmental phe-

nomena. Census data must therefore be transformed into usable formats to respond to the

needs of stakeholders.

3.236. For some countries, the fundamental paradigm shift in the 2020 round of population

and housing censuses is the utilization of statistics to increase public knowledge related to the

progress of society and for transparency, mutual accountability and governance, results-based

management and transformation. e role of statistical leadership is to anticipate and deﬁne

measurement of policy questions. e increased use of statistics by government, business

and citizens at large will drive diﬀerent and better results and thereby succeed in mobilizing

society for change.

3. 237. e population and housing census represents one of the pillars for data collection

on the number and characteristics of the population of a country and is part of an integrated

Principles and Recommendations for Population and Housing Censuses, Revision 3124

national statistical system, which may include other censuses (for example, agriculture), sur-

veys, registers and administrative ﬁles. It provides at regular intervals the benchmark for

population counting at national and local levels. For small geographic areas or subpopula

tions it may represent the only source of information for certain social, demographic and

economic characteristics. For many countries the census also provides a unique source for a

solid framework to develop sampling frames.

3.238. While the importance of disseminating census results to the fullest extent possible

should be stressed, there are, nevertheless, some things that are essential for the national sta

tistical or census oﬃce to keep in mind. Among these is the prerequisite for national statistical

and census oﬃces to ensure openness and transparency in the way the results are disseminated.

It is equality important that national statistical and census oﬃces maintain professionalism

and demonstrate neutrality and objectivity in the presentation and interpretation of the results

and are free from real or perceived political interference so that the objectivity and impartiality

of the statistics is assured. is in turn will build trust in and acceptance of the results. Fur

thermore, the disseminated census results should be of suﬃcient quality to meet user needs,

and safeguards should be in place to ensure individual information is kept conﬁdential.

B. Plans for census products and data dissemination

3.239. In order to maximize the utilization of results from their population and housing cen-

suses, national statistical and census oﬃces should have a sound dissemination programme

whose objective is to promote the beneﬁts and applications of census data. e statistical

or census oﬃce should develop and implement an eﬀective strategy for producing and dis

seminating output products and providing related services based on the demonstrated needs

of the diverse users of census data. What follows are some salient issues for an eﬀective dis

semination programme.

1. Developing a dissemination strategy

3.240. A census is not complete until the information collected is made available to users

in a form suited to their needs. In order to fulﬁl this requirement, it is essential to develop a

strategy for producing and disseminating outputs taking into account all potential users of

the data. e objective of the dissemination process is to ensure that census products and ser

vices meet data user needs. is in turn requires identifying potential users of census data and

their demonstrated needs so that appropriate products and related services can be developed.

3.241. A wide range of dissemination strategies must be developed for meeting the require

ments of diﬀerent users. Appropriate technologies and media need to be identiﬁed for eﬀec-

tive and easy dissemination of census data and information. Use of GIS makes information

more user friendly by including thematic maps. Census maps in printed or digital form

should be included in the overall dissemination programme of a population and housing

census. Budgetary provision should be made in the initial planning stage itself. In addition

to preparing maps for the census reports, countries should also produce a population atlas

and try to make most data available in a GIS on a CD-ROM, at diﬀerent and nested levels

of administrative geography, thus exponentially increasing the usefulness and utilization

of census data. A number of census products have been developed that allow data users to

visualize and customize data on maps. ese are available as online and oﬄine computer and

mobile applications. Depending on the need and resources available, the development of such

products should also be explored.

125Census operation activities 125

3.242. A number of key elements should be taken into account in the development of a strat-

egy for census data dissemination, including identifying the diverse categories of users and

their data needs and uses through (a) consultation, (b) products to be developed, (c) the media

of dissemination, (d) metadata to aid in the interpretation of the results, (e) conﬁdentiality

and privacy measures, (f ) assessing the required technologies to meet user needs, (g) dis

semination policy, (h) quality assurance in terms of accuracy and timeliness, and (i) available

ﬁnancial and human resources. e ﬁrst ﬁve elements are covered in subsequent sections of

this chapter. e remaining are summarized below.

• Tech nolog y. Given the widespread availability and use of technology for easier

production and access to census products, national statistical and census oﬃces

should evaluate which ones are suited to the needs of their data users, taking into

account budgetary and human resource constraints. ese technologies include

use of GIS and thematic map generators, new sophisticated data base systems,

and interactive web access, including client-customized table generators.

• Dissemination policy. When planning the dissemination programme, a dissemi

nation policy should be established as well. is policy should cover issues such as

ways of marketing the census products, which in most cases means mainly how

to inform a wide range of potential users about the availability of the products.

A clear pricing policy should also be determined, and a decision made as to the

conditions under which external distributors are allowed to disseminate census

data. e dissemination policy should also cover issues connected with the pro

tection of the conﬁdentiality and privacy of personal data, and the measures that

will be used for each of the diﬀerent products.

• Quality assurance. Quality refers primarily to user needs and satisfaction. Even

if data are accurate, they do not have suﬃcient quality if they are produced too

late to be useful, or cannot be easily accessed, or conﬂict with other credible

data, or are too costly to produce. erefore, quality is increasingly approached

as a multidimensional concept. It has been suggested that the output of any

statistical exercise should possess the following attributes: accuracy, relevance,

reliability, timeliness, punctuality, accessibility, clarity, coherence, comparabil

ity and metadata.

Management of quality in census dissemination is driven

by concerns to (a) deliver relevant products and services while (b) maintaining

accuracy of the data, and (c) timeliness and predictability of data release within

agreed cost constraints.

• Budget and human resources. Two obvious key elements (usually constraints) in

the development of strategies for census data dissemination are the budget that can

be allocated and the availability of human resources. With the high relevance of

new technologies in all the census stages, and in particular for data dissemination,

this is a factor that needs to be carefully analysed when deciding about the speciﬁc

strategy of census data dissemination. e alternative to the recruitment of human

resources may be contracting out some dissemination activities, in particular those

connected with the development of more sophisticated systems. However, this

solution needs to be carefully considered. It is extremely important to ensure that

the contractor is committed to the census project until its very end and that at least

some of the new abilities remain in the organization for further use.

(a) Consultation with data users

3.243. e demand for and use of statistical products and services must drive all census

operations. National statistical and census oﬃces should have a sound strategy for developing

suitable products and services to respond to the diverse needs of data users so as to promote

United Nations Statistics

Division, Guidelines for the

Template for a Generic National

Quality Assurance Framework

(NQAF) (2012), available from

http://unstats.un.org/unsd/dnss

/docs-nqaf/GUIDELINES%20

8%20Feb%202012.pdf.

Principles and Recommendations for Population and Housing Censuses, Revision 3126

the utilization of census results. Such strategies should be based on an active dialogue with

the users regarding their needs in terms of products and the format of those products.

Anticipate user needs and provide support

3.244. e user consultation process in terms of census products is a major factor in the

development of a dissemination programme. e type of consultation discussed in this sec

tion complements the consultation that is undertaken to determine census content (see para-

graphs 2.98-2.102). e work done at this stage of the census is important in achieving the

objective of ensuring that the census is relevant to users, which is a major indicator of the

quality of the census. e selection of suitable census data products and related services

should be guided by a detailed assessment of user requirements.

Create systems and infrastructure for access to and use of census results

3.245. Plans for what and how products will be disseminated should be made early in the

planning process and shared with potential users in order to get their feedback. Based on

this feedback, the national statistical or census oﬃce can tailor its data dissemination pro

gramme to suit the requirements of the users. Maintaining good communication and obtain-

ing feedback from users is also important for making modiﬁcations to products and services,

including being able to respond to user requests that become known later in the programme.

3.246. Based on the foregoing, it is important to note that the supply of census products and

services goes far beyond the ﬁrst couple of years after the census. It is important, therefore,

that budget and human resources are available for many years after the end of census collec

tion activities.

(b) Plans for outputs

3. 247. It is important for census oﬃces to consult stakeholders and identify their needs dur

ing the preparatory phase to proactively anticipate the type and format of census products

to be produced. is is to ensure that census products are relevant, responsive and add value

to the current policy questions and stakeholder needs. It is recommended that census oﬃces

include a census products plan and budget as part of the preparatory phase.

3.248. A wide range of statistical products can be made available to the public, the private

sector, government agencies, local authorities and the academic and research communities.

A detailed plan for producing diﬀerent census outputs should be guided by early user consul

tations (see paragraphs 2.98-2.102) to ensure data and information requirements will be met

in a format commensurate with user needs and demands; such a plan will also be a useful

guide to prioritizing data processing and tabulations.

3.249. With the rapid development of technology, census data users have an increasing inter

est in a broad range of products and services from the census organization. e types of out-

put that census oﬃces may produce and disseminate must be current and may include printed

products, static electronic products, interactive electronic products, customized products,

user-interactive products and special audience products and services. Partnerships with key

stakeholders are encouraged in the development of the various census products.

3.250. Some data users will need specialized products that the census organization is not

planning to produce as part of the general census programme. It is recommended that the

census organization establish a service to meet such specialized requests. Pricing of special

products and services may be included in a pricing policy.

3.251. Printed publications, despite their production cost, remain in many countries the

preferred vehicle for dissemination of the main results. Target dates for publication should

127Census operation activities 127

be determined well in advance and processing and printing programmes should be planned

accordingly. In addition to traditional methods of printing, there are various methods of

reproduction available that are fast, economical and of good quality, and these should be inves

tigated. For an increasing number of users, computer-readable magnetic and optical media

and online electronic data dissemination are a better means than printed paper, based on the

factors of cost, storage capacity (and therefore weight of documents), ease of reproduction and

direct availability of the data for further computer processing. In addition to the processed

tabulations, sample data at the unit level are also provided by some countries for research

purposes. In such cases, the sample should be carefully drawn to ensure an adequate level of

representation while at the same time ensuring that anonymity is not compromised. Some

countries have also adopted very creative techniques for data dissemination and visualization.

e development of such data products should be part of the planning process of the census.

3.252. Not all of the processed materials need to be disseminated widely or in a single format.

Tabulations required by only a few users can be supplied in unpublished form. Some data may

not be tabulated until they are required at a later date. e information stored in the census

database allows fast and relatively inexpensive production of additional tables. Countries may

oﬀer on-demand services to provide census information to users who require tables or other

outputs not produced, or aggregates not available, through other means. If suitable electronic

dissemination is available, customized tabulations and applications might also be designed

and extracted directly by end users. In this case, the census organization should prepare in

advance and then implement an authorization and security policy, so that the risk of breach

ing conﬁdentiality in data provided to outside users is avoided.

2. Tabulation programme

3.253. In most countries, the tabulation programme represents a compromise between the

full range of desired tabulations and the limits imposed by practical circumstances. To ensure

that this compromise is made transparently and eﬃciently it is important that planning the

census dissemination task is started at the earliest stage of the census development cycle by a

round of user consultations. Once the census-testing programme has identiﬁed a practicable

range of data items to be included in the questionnaire, data users should again be consulted

on the speciﬁc cross-tabulations required and the relative priority for their production. It is

essential that the programme be outlined suﬃciently early so that the procedures and costs

involved are investigated thoroughly before a ﬁnal decision is reached. e type of question

naire and the method of enumeration may limit the kinds and amounts of data that it is

possible to collect. Publication time and costs, and the data-processing resources available,

will determine the number and complexity of the tabulations that can be produced within a

reasonable time. is will enable prospective census data users to make ﬁrm plans, and the

census data processing staﬀ to complete all systems analysis, programming and testing work

in a timely manner.

3.254. e tabulations presented on the website of the United Nations Statistics Division are

those fulﬁlling the most essential or generally required information. e databases of census

information can be used throughout the intercensal period to address the needs of specialist

users for whom these tabulations are not adequate.

3.255. It is important to plan the tabulation programme in such a way that ﬁnal results can

be issued within a reasonable period of time after the enumeration and before the informa

tion has become out of date for current needs. It is desirable that the details of the tables

be prepared and the order of their preparation be decided early in the planning, so that the

processing of the data is not be delayed.

Principles and Recommendations for Population and Housing Censuses, Revision 3128

3.256. Special tabulations may be requested at any time after the census enumeration. Once

the census database has been produced by recording, editing and correcting the raw data,

tabulation software packages can be introduced. ese packages allow fast and relatively

inexpensive production of tables for selected subsets of the total database or for alternative

aggregates, assuming the information has been preserved in the database in terms of the

needed detailed classiﬁcations.

3. Dissemination geography

(a) Linking collection to dissemination geography

3. 257. An essential feature of the population and housing census is its diversity in terms

of the geographic level at which data can be disseminated. is is due to the ability of the

census to produce statistics that can be disseminated at the lowest geographic level (small

area), through a geographic hierarchy up to the country level. Consequently, one of the earli

est decisions in census planning relates to the administrative and geographic areas for which

census data on diverse socioeconomic characteristics of the population will be reported and

disseminated in order to satisfy the needs of the various data users.

3.258. In addition to administrative units, most countries will have a number of other sets

of areas that are used for diﬀerent purposes and for which census data will need to be com

piled.

Such areas, which have special uses, include health regions, electoral districts, urban

agglomeration or metropolitan areas, and utility zones (water or electricity supply districts). It

should be noted that some of these areas may not ﬁt perfectly into the administrative hierar

chy of the country. It is important, therefore, that to the extent possible these reporting units

are taken into account when designing enumeration areas in order to facilitate generation of

census data for these regions. is draws attention to the fact that when delineating collection

geography (enumeration areas), it is essential that dissemination geography is kept in sight.

3.259. Two somewhat diﬀerent methods are available to provide the census with a ﬂexible

capability for generating tabulations in terms of a wide variety of geographic aggregations,

including those needed for public and private sector data uses at the local level. e ﬁrst

method simply extends the traditional hierarchical system for coding all major and minor civil

divisions so as to cover at the lowest level of the enumeration area, sometimes referred to as

the “enumeration district”. e second method, which at greater cost permits ﬁner geographic

speciﬁcity, is usually based on some coordinate or grid system, such as latitude and longitude.

is method is often referred to as a “geocoding system”. Particularly in the absence of a com

prehensive system of street names, numbers or similar addresses, the ﬁrst method, which uses

the enumeration area as the key unit for the production of smallarea data, is to be preferred.

3.260. e fact that census data, whether published or unpublished, are available by enu

meration area provides for considerable ﬂexibility. Such ﬂexibility can be of value given that

the geographic divisions used by various branches of the administration or by other data users

do not always coincide and may therefore require diﬀerent regroupings. Moreover, when

changes are planned in administrative boundaries, tabulation of census data by the planned

new entities can also be facilitated through the enumeration area approach. However, if

these changes cross enumeration area boundaries, and it is decided to try to retabulate the

census according to the new boundaries, very complex recoding of individual records may

be involved. As an alternative, statistical concordances, showing the quantitative relationship

between the previous and current classiﬁcations, could be used. Further, where buildings

or housing units have been geocoded, these geocodes can be used to directly allocate each

household to the correct area under either classiﬁcation.

Handbook on Geospatial Infra-

structure in Support of Census

Activities, Studies in Methods,

No.104 (United Nations publica-

tion, Sales No. E.09.XVII.8).

129Census operation activities 129

(b) Uses of small area geographic data

3.261. Censuses provide data from the highest to the lowest geographic levels of aggrega

tion. Tabulations from census results yield relevant statistics for any reasonable combination

of characteristics for the country as a whole, regions or provinces, down to small areas such

as localities, and even enumeration areas and geographic grids. is important feature of

the census makes the data amenable to the development of estimates of variables of inter

est for small and local areas in two major ways: directly from the production of tables from

the microlevel data for the required characteristics, and indirectly from applying estimation

techniques by combining other sources, such as sample surveys and administrative statistics

to the population and housing census results.

3.262. Census data are typically aggregations of data for many individual small areas, and

may commonly be used to study large regions or entire nations. Data for small areas enable

the user to obtain statistical information about any number of local areas of interest, in addi

tion to showing variations among small areas in individual parts of the country. Modern

computer technology greatly facilitates the utilization of census results for analysing the

information for small areas, limited only by issues of conﬁdentiality and collection design

and statistical disclosure when cell entries in cross-tabulations become very small. For exam

ple, the analysis of whether population programmes have aﬀected the level of fertility at a

regional level may be carried out by analysing data from the smallest administrative units

so as to observe local variations and produce more accurate assessments of cause and eﬀect.

3.263. Implementation of various national social and economic development programmes is

a function of the state, province or lower levels of government in many countries. Results of

population and housing censuses are useful for planning and monitoring development at the

local area, small town level or small area. Small-area data are also important for private busi

nesses in developing their distribution and marketing strategies. For example, information on

housing demand from the population and housing census may be used by local authorities,

local real estate companies, building and housing development contractors, and manufactur

ers of construction materials, among others.

3.264. Census data have been traditionally aggregated by various types of administrative

units (for example, towns, villages, provinces and electoral units). In addition, other types

of small areas are sometimes used in the census that are essentially statistical in nature (for

example, census tracts and grid squares that do not change from census to census, and very

small units such as city blocks or block faces). ere have also been increasing demands for

small-area data that cut across the local administrative boundaries. Population and housing

censuses provide a powerful tool for assessing the impact of population on the environment,

for example on drainage basins and on water resource management systems. e spatial

units for such a study may combine a group of local administrative areas. In this situation

the availability of census databases with mapping capability (see paragraphs 3.107-3.108) is

of great importance.

3.265. Tabulations for small areas may be prepared on the basis of the resident population

of each area or on the basis of the population present in each area at the time of the census.

Tabulations relating to the resident population are produced for the apportionment of rep

resentation in legislative bodies, the measurement of internal migration, the computation of

measures of fertility and mortality by place of residence, and the planning and administration

of such services as schools and housing, which have relevance only to the resident population.

Tabulations based on the population present in the area at the time of the census are useful

where this population is considerably larger than the resident population and thus raises the

demand for products and services above the level required by the resident population alone.

e combined population and housing census may also be used to make comparisons of

Principles and Recommendations for Population and Housing Censuses, Revision 3130

resident and daytime populations in speciﬁc localities, if an item on place of work is included

in the population census. It is therefore important that users express their needs for particular

data disseminated in a given format, based on the usual residence or place of enumeration,

at an early stage of census preparations.

3.266. It was elaborated in part one, chapter I, how the population and housing census plays

an essential role in the economic and social components of the national statistical system

and also serves as a sampling frame for sample surveys. Another signiﬁcant way in which the

census results complement survey statistics is in small-area estimation, whereby models con

structed from survey data are applied to census results for any speciﬁed geographic area. is

estimation approach may be used for generating such indicators as employment, poverty and

other economic indicators, for which measurement is required at the local area level.

e

application of small-area estimation techniques to poverty measurement and mapping is an

important extension of the use of census results. Many countries perform midyear population

estimates at the national level; however, the application of small-area estimation techniques

can be used to compile midyear population estimates at subnational and local levels. If such

use is contemplated, it would need to be taken into account during the planning stages of

the census exercise, when decisions about topics to be included in the census are being made.

4. Mode of dissemination of outputs

3. 267. As has already been mentioned, a census is not complete until the information col-

lected is made available to potential users in a format suited to their needs (paragraph 3.240).

Consequently, meeting the needs of data users means that the data producer should not only

provide data products to the users, but should also provide them in formats that are suitable

to the needs of the users. e information in the products may be included in published

tables and reports for general distribution, produced as tables in unpublished form for limited

distribution or stored in a database and supplied upon request, or disseminated online either

as static or interactive products.

3.268. It should be noted, however, that regardless of mode, all dissemination is subject

to issues of (a) quality assurance; (b) possible disclosure of information about identiﬁable

respondents; and (c) copyright and ownership. In addition, the issue of cost recovery has

become important to many statistical organizations. Each medium of dissemination has its

advantages and limitations, and the choice of one or more of them depends on the context,

and on the intended categories of users. In most instances, these methods complement each

other and can provide eﬀective ways to reach out to the public and private sectors.

3.269. When data are provided in electronic form, special attention should be given to pro

viding users with easy means of data retrieval. e options for obtaining the relevant meta-

information and data should be accessible in standard and contemporary formats.

(a) Publication of printed tables and reports

3.270. Although more and more countries use software for online dissemination of their cen

sus results, printed publications remain an often-selected choice for the dissemination of the

main census results. At least for the present, they reach out to the largest number of potential

census data users. Paper media do not require that the user has any particular equipment,

software or technical skills.

3.271. It is important that plans be made and suﬃcient funds be allocated to ensure pub

lication of the tabulations of widespread interest. e ﬁnal tabulations should be presented

and explained in a way that will facilitate their extensive use. e data should be shown for

appropriate geographic and administrative divisions and classiﬁed by important demographic

Measuring the Economically

Active in Population Censuses: A

Handbook (United Nations publi-

cation, Sales No. E.09.XVII.7).

131Census operation activities 131

variables. e census publications should also contain information on how the data were

collected and processed, results of available evaluation studies, and appraisals of the substan

tive signiﬁcance of the results presented. In addition, a suﬃcient number of maps should

be provided in the census publication to allow the identiﬁcation of the geographic units for

which the statistics are presented.

3.272. Using tabulation programs to produce output directly for publication allows the tra

ditional method of dissemination of statistics through printed reports to be integrated more

closely and more inexpensively with the statistical production process. If the software used

for tabulation cannot produce camera-ready output, the ﬁles containing output tables can be

moved into a document that could be assembled using desktop publishing or word-processing

software. Manual retyping of tables once generated should be avoided as much as possible to

prevent transcription errors and delays.

3.273. e choice of how the actual printing is to be done entails in fact a trade-oﬀ involving

quality, cost and speed. e best results can usually be obtained by sending the documents

in computer-readable format to a professional printing plant. is will allow high-quality

typesetting and the use of supporting colours. Alternatively, master printouts can be made in

the census oﬃce and sent to the printer for cheaper duplication or oﬀset printing. ere are

also aﬀordable high-speed printing systems that can be directly controlled by the computers

in the census oﬃce.

3.274. Target dates for publication should be determined well in advance and processing, and

reproduction programmes should be planned accordingly. In addition to traditional methods

of printing, there are various methods of reproduction available that are rapid, economical

and legible, and these should be investigated.

(b) Dissemination on computer media

3.275. For an increasing number of users, computer-readable magnetic and optical media

are the preferred medium of dissemination. is is because data in this form are often less

expensive to obtain, copy and store. In addition, they are directly available for further com

puter processing and analysis.

3.276. Technologies such as CD-ROM and DVD-ROM provide forms of distribution for

large data sets that are not subject to frequent change or updating. Standard CD-ROMs and

DVD-ROMs are read-only optical media. ey have a very large storage capacity, they are

durable, and they can be produced inexpensively. Because the results of a particular statistical

enquiry such as a census are supposed to be ﬁnal, dissemination on a read-only support should

be satisfactory. Equally, widespread dissemination of census statistics uses ﬂash drives or

memory sticks, which are increasingly able to carry extremely large volumes of digital content.

3. 277. Further development of media for storing digital content will inevitably have an

impact on the dissemination of census results. It is thus necessary to keep abreast of develop

ments in this ﬁeld in order to meet the changing needs of users of census statistics.

3.278. Online dissemination of all kinds of information, including statistical information,

has increased with new innovative formats for displaying census data. e advantages of

online dissemination are found primarily in terms of speed, ﬂexibility and cost, and making

results accessible to a wide range of data users. e information is available to the user as soon

as the provider has uploaded it to the server and cleared it for access by users. Information

can be static or dynamic. e cost to the user is limited to the expenses of communication

with the Internet service provider, plus whatever charge the information provider is placing

Principles and Recommendations for Population and Housing Censuses, Revision 3132

on top of these. ere is no expense involved in the production and distribution of printed

materials or other data supports. ere are however ﬁnancial resources needed for the imple

mentation of the online data platform and potential training needed for staﬀ to operate such

technologies.

3.279. Online dissemination of data was common well before the Internet gained promi

nence. e simplest option open to statistical organizations was bulletin board systems, now

largely replaced by Internet and intranet websites. e same website could be used for both

internal and broad community communication, with the granting of access rights in certain

areas to privileged users only. Security measures, including passwords and callback proce

dures, can be used to exclude unauthorized users from reaching these areas. is is however

risky, since resourceful hackers may ﬁnd their way around the barriers and gain entrance to

conﬁdential information. Firewalls are hardware or software security systems that limit the

exposure of a computer or network to malicious inﬁltration from an external location. e

census oﬃce website is probably the ﬁrst dissemination medium where Internet-connected

users would look for census information. It is recommended that microdata should not be

stored on a website in direct contact with the public. It is also recommended that a powerful

ﬁrewall constitute a security layer between the website that is visible to the public and the

working network of the census oﬃce. Websites of public administrations are under constant

attack from hackers and very sophisticated security measures must be adopted when “opening

up” on the Internet. Internet security, despite being an issue of a technical nature, has to be

mandated, demanded and resourced by the highest levels of management of the census oﬃce.

3.280. An Internet website can be used not only to make information available as soon as it

has been cleared, but also for other forms of communication with users. Possibilities include

online ordering of publications and one or more receiving areas for questions that would be

answered later through the same medium by appropriate specialists. One such area could be

the census forum or “chat room”.

3.281. Internet websites may support “door” or “gateway” applications that allow users to

run outside programs on the computer on which the Internet web server operates. Interac

tive access to census outputs can be oﬀered to most types of databases and census products,

including reports, publications, tables, maps and graphs. For example, there may be a data

base of aggregated census data for small areas or a microdata database that users can access

in this way. When the required data are not readily available, users could run an on-the-spot

query to obtain and retrieve results that satisfy their needs. is can be done by oﬀering to

Internet users census microdata samples and an interactive tabulation system. Users can then

select records from these data sets that satisfy certain parameters and compute statistical

information, such as two-dimensional cross-tabulations of either original or recoded vari

ables. Program execution by users on the outside, however, raises important questions of cost,

eﬃciency and conﬁdentiality, which have to be resolved. For reasons of eﬃciency, it is recom

mended that information that is provided or likely to be heavily requested by users accessing

the census website be made available in a static format, which is faster to download. Letting

the user run data extraction on online databases, which would be a dynamic way of access

ing the census information, is more resource-consuming and should be the second choice for

users needing more detailed data than those available through static pages.

3.282. Other media such as social media are useful in disseminating census information

targeted at diﬀerent sectors of the population. More generalized media, such as the radio,

television programmes, newspapers and press conferences, oﬀer the possibility of reaching

out to sectors of the population not otherwise reachable.

3.283. A hybrid solution for data dissemination that appears to combine the advantages of

several approaches is one whereby the statistical or census organization makes basic data avail

133Census operation activities 133

able to users on a computer-readable medium, usually through a website or optical media,

while additional information may be provided by telephone or some other online protocols,

such as ﬁle transfer protocol sites. is will usually take the form of a package that contains

basic data, metadata and data browser software. e basic data may contain existing time

series, report ﬁles and the like, as well as country and region maps that can be used to generate

thematic maps with various indicators. Maps made available to general users need not ensure

the same geographic detail as maps used for enumeration areas. Lighter versions of maps at

any subnational level may be provided to the general public, and more sophisticated and

detailed ones to those fewer users who would actually need an increased level of detail. It is

thus important that the website specify the instructions on how to contact oﬃcers responsible

for special dissemination needs.

3.284. For some users, if the particular statistical information is not yet available on the phys

ical distribution medium, special access may be granted, provided that adequate screening

of their credentials and security checks are performed, to protected areas of the Internet site

where up-to-date census information becomes available. Since opening up online resources to

users has to be planned carefully and a clear policy established in advance (so that criteria for

deciding whether or not to grant access are unambiguous), it is not recommended. Instead,

provision of an online data tabulation system for expert end users is advised.

5. Conﬁdentiality and privacy

3.285. According to principle 6 of the Fundamental Principles of Oﬃcial Statistics, “Indi-

vidual data collected by statistical agencies for statistical compilation, whether they refer

to natural or legal persons, are to be strictly conﬁdential and used exclusively for statistical

purposes”.

Maintaining data conﬁdentiality is an indispensable element of maintaining the

trust of respondents. If respondents believe or perceive that a national statistical or census

oﬃce will not protect the conﬁdentiality of their data, they are less likely to cooperate or

provide accurate data. is in turn aﬀects the accuracy and relevance of the statistics.

3.286. All the information stored in the census database allows the production of tables both

for very small areas (such as enumeration areas or villages) and for all individual units in these

areas. erefore, when a census database is constructed, not only technical considerations

but also the maintenance of conﬁdentiality and the protection of individual privacy—which

must be a primary consideration in designing the data collection and data processing pro

gram—must be taken into account. Accordingly, microdata, such as name and local address,

or the unique characteristics that permit the identiﬁcation of individual respondents, must

be removed from the database or otherwise altered.

3.287. e same care must be taken if a transcription of information from original question

naires (that is to say, from a representative sample) is needed for use by qualiﬁed agencies

and research institutes engaged in special studies beyond the purview of the regular census

programme. Such needs have sharply decreased with the almost universal use of computer

technology. However, when such a procedure is possible under the census law, individual

privacy should be ensured and no exception should be authorized.

3.288. e ever-increasing demand from users for more data, especially microdata and at

lower geographic levels, and also with more technological advancement for data linking, par

ticularly over the Internet, has created more challenges for managing data conﬁdentiality. As a

result, national statistical and census oﬃces should examine the data and make modiﬁcations,

when necessary, prior to dissemination of the data. e objective of the modiﬁcations is to

prevent identiﬁcation of individual respondents, and also intentional or inadvertent disclosure

http://unstats.un.org/unsd/dnss

/gp/fundprinciples.aspx.

Principles and Recommendations for Population and Housing Censuses, Revision 3134

of their personal information. is is particularly the case when microdata are disseminated

and when data are linked to location, such as with the use of GIS.

3.289. Data protection methods range from simple cell suppression to elaborate statisti

cal applications for entire databases. e approaches used to limit disclosure are tailored

according to the type of data and the product to be disseminated. e methods diﬀer based

on whether the underlying data are microdata (individual units) or aggregate estimates (for

matted as frequency counts or aggregate magnitude data).

Diﬀerent techniques are also

employed depending upon the type of data product to be released (microdata ﬁles or tables).

e three most common practices that limit disclosure in microdata are (a) eliminating infor

mation that directly identiﬁes individuals; (b) suppressing data that may indirectly identify

individuals; and (c) introducing uncertainty into the reported data.

6. Metadata

3.290. In order to assist data users to better understand and interpret the data, it is important

that there is adequate documentation providing a complete and clear description of the pro

duction process, including data sources, concepts, deﬁnitions and methods used. is infor-

mation represents metadata that, it is recommended, should accompany all census products.

Metadata will promote transparency and credibility of census results. Also, dissemination of

census products with accompanying metadata ensures harmonization and comparability of

census data with other data sets.

(a) Deﬁnition and content

3.291. Metadata comprise descriptive and structured information or documentation about

data that informs users about the content, quality and condition of data. In this context,

metadata provide guidance on the proper usage or interpretation of data by providing infor

mation on the processes of production and describing the structure of data sets, thereby

making it easier to retrieve, use or manage the data. Metadata constitute a standardized way

of organizing data and can be categorized as follows: (a) reference metadata, which allow

understanding and interpretation of the corresponding statistical data by describing the con

cepts, deﬁnitions, methodology and quality of data, production and dissemination processes,

data access conditions, etc.; and (b) structural metadata, or “data about data”, which provide

information about the structure of the data set and act as identiﬁers and descriptors of the

data, making it possible to properly identify, retrieve, browse and further process the data.

(b) Uses of metadata

3.292. e need for comprehensive and easily accessible metadata to better understand the

statistical data being presented cannot be emphasized enough. Metadata are a key element of

census dissemination to ensure that the underlying concepts and deﬁnitions are well under

stood and that the results are well interpreted. Metadata are used by people or systems to

make proper and correct use of statistical data in terms of capturing, reading, processing,

interpreting, analysing and presenting the information.

3.293. All tabulations should include the following metadata or references to where this

information can be obtained: census questions; reasons why they are asked; conceptual deﬁ

nitions (census dictionary); geographic hierarchies used; changes since the previous census

with regard to content, operational methods or geographic boundaries; and quality indica

tors such as coverage rates and item non-response. Data ﬁles must also be accompanied with

metadata, including names and codes for common variables, personal ﬁles and household

ﬁles. If a long-form sample is used in the census, metadata should also provide information

P. Doyle, J.I. Lane, J.J.M.

Theeuwes, and L.V. Zayatz, eds.,

Conﬁdentiality, Disclosure and

Data Access: Theory and Practical

Applications for Statistical Agen-

cies (Amsterdam, Elsevier, 2002).

V.A. de Wolf, “Issues in accessing

and sharing conﬁdential survey

and social science data”, Data Sci-

ence Journal, vol. 2, No. 17 (2003),

pp. 66-74.

135Census operation activities 135

on the sampling variability of the results. When the census tabulations include suppressed

data cells due to small numbers, the metadata should also include a methodological note on

the rules and methods of suppression. Metadata should be preserved for future reference.

With the increased use of technology, properly designed metadata systems for web-based

applications are recommended.

7. Promotion of, and training on, uses of census data

3.294. e main purpose of a census is to collect, process and disseminate information that

will be used as the basis of informed, evidence-based decision-making. e beneﬁts of this

approach to decisions are not always apparent to users, especially in situations where other

approaches may have been used in the past. It is therefore important to promote such uses of

census results among users.

3.295. In other cases, users may be willing to use the information but require additional

training to more fully understand the data. Such training may be usefully combined with

training in statistical dissemination techniques or uses of more advanced data products. At

a very basic level, some users may require training in such mundane issues as how to contact

the national statistical oﬃce, or how to ﬁnd the information they require within the systems

of that oﬃce, or how to use the website and other electronic applications and tools.

3.296. Whichever approach is taken to enhancing promotion and training in the use of

statistical data, a number of strategic issues need to be addressed. ese include:

(a) Ensuring that the needs for training are identiﬁed early in the census planning

process and that required funds are included in the census budget. In many cases

the courses requested by users will be speciﬁc to those users; in such cases it may

be desirable to request the user to provide funds to cover the marginal (or full)

costs of the course.

(b) e proposed courses or materials should be fully integrated into the overall census

advocacy or training programme. It is essential that messages about the use of data

fully reﬂect the messages given when initially advocating conducting the census

or seeking public cooperation with and participation in the collection phase.

demand for training will far outstrip the ability of the statistical oﬃce to deliver

it. In this case it will be necessary for the statistical oﬃce to have prepared trans

parent strategies that (a) identify those areas in which the statistical oﬃce wishes

to participate (for example, dealing with lifeline clients, and topics on which the

statistical oﬃce has particular knowledge or expertise); (b) establish partnerships

with other bodies to provide training; (c) use approaches other than classroom

training to provide learning-at-a-distance opportunities (for example, e-learning);

and (d) have a pricing regime to cover costs where this is seen as desirable.

3. 297. e list of target audiences and topics for such training must be determined by coun

tries. It should be noted, however, that basic training in the use and interpretation of the

results of one census is a very strong method of advocating support for future censuses. It is

thus recommended that countries consider development of a basic course in (a) potential uses

of census data; (b) how to access census data; (c) interpretation of census data at the broadest

level, including the interpretation of its completeness and level of accuracy; and (d) spatial

analysis. e target audience for such training should be key decision makers in the political

and administrative hierarchy of the country. It should be outlined that the uses of census data

at the local level (small areas) oﬀer substantial potential for constructive use of census data;

spatial distribution of population by age and sex, for example, provides an ideal framework

Principles and Recommendations for Population and Housing Censuses, Revision 3136

for local oﬃcials to address the most pressing issues of their constituents, such as location of

schools, utilities, service delivery and so forth.

3.298. A second group of key importance are members of the mass media, such as print, radio

and television journalists. A focus on training such personalities is important because they

can carry the message to many other people. is will assist in the general raising of aware

ness in the population at large, as well as in generating an awareness of the census among

the governmental, academic and business users who may not have contact with the statistical

oﬃce on a regular basis. Obviously such training should be completely integrated with the

overall public relations and advocacy work.

3.299. A third group to be targeted are schools, both students and teachers. A focus on train

ing of teachers to use census data in the mathematics and geography curricula creates aware-

ness among children about using statistics in decision-making and allows them to develop

numerical skills using real data.

3.300. A fourth group to be targeted are geographers, with the aim of integrating census and

survey data with GIS shapeﬁles in order to perform spatial statistical analysis. is training

will enable specialists to better present statistics in space.

3.301. A ﬁfth group to be targeted are non-users of census data. A number of stakeholders

are unaware of how census data can be used in their area of work to make evidence-based

decisions. Countries need to aim to increase the usefulness of census data by identifying

non-users. User segmentation will be a valuable source of information to identify possible

non-users to be targeted.

3.302. A sixth group to be targeted is the research community. e focus of the training and

demonstrations will be on the application of various statistical techniques to census data. is

will improve utilization of census data.

C. Census data dissemination: products and services

1. Provisional and ﬁnal results

3.303. Some countries release provisional results very soon after enumeration is completed.

Subject to change once the full data-processing and veriﬁcation operations have been com

pleted, they nevertheless provide a general picture of population trends. Provisional census

results may be processed manually or by computer. For reasons of eﬃciency and quality, the

use of computers is always preferable. e ability to verify data quality during the enumera

tion phase with the help of validation programs, quick indicator reports, data consistency

reports, and tabulations greatly increases the conﬁdence with which provisional results can

be announced. Provisional results will normally cover information only on total population

by sex and by major division. e number of households and housing units may also be

derived easily from this exercise. e preliminary result of the census can be reported right

after the end of the census by utilizing the summary of household lists without individual

data processing. is can be possible as the summary usually includes the total population,

households and housing unit in each major division.

3.304. e ﬁnal census results will be the output of the main tabulation programme. Tabula

tions may be based on all of the returns or on a sample. If some of the topics are collected on

a sample basis only, proper weights will have to be applied in the tabulation stage to produce

valid national estimates. In addition, the census oﬃce should be prepared to facilitate the

production of tables requested by researchers and users (see paragraphs 3.392-3.398).

137Census operation activities 137

3.305. Since provisional and ﬁnal results may diﬀer (for example, the summaries on which

provisional results were based might contain errors), it is important that data users be made

aware of and warned about the possibility of such diﬀerences. Implications of using provi

sional population counts must be outlined. It is recommended that quality assurance pro-

cesses be put in place to minimize variances between the provisional and ﬁnal results.

3.306. e ﬁnal census results must be published as soon as possible. Countries may aim

to publish the basic, essential results within one year of enumeration. e use of technology

may reduce the time between the release of the provisional and ﬁnal results, which may over

time render provisional results obsolete. e dissemination of the ﬁnal census results must

be part of a comprehensive dissemination strategy and plan. e schedule and description of

upcoming releases of ﬁnal results and products should be made public early in the process

to maintain interest by the public in the census (see also release calendar, paragraphs 2.114-

2.118). e releases can be staggered, from simple, descriptive one-page summary fact sheets

covering a country’s major geographic divisions initially, to more comprehensive tabulations

and descriptive reports later on.

2. Census reports

(a) Basic reports

3.307. Every eﬀort should be made to publish the principal results of a population census

(such as those on age, sex and geographic distribution of the population) and of a housing

census (such as a geographic distribution of sets of living quarters, households and population

by type of living quarters) as soon as possible after the enumeration, otherwise their useful

ness and the extent of their interest to the public will be diminished. With technological

advancements, the time required for processing and tabulating results has been signiﬁcantly

reduced. As a result, collection restrictions, in terms of cost and accuracy of the data, have a

greater relative weight in determining the number and complexity of the tabulations that can

be produced and disseminated. e tabulation plan must respond to user needs.

3.308. e population and housing census tabulations presented and illustrated on the web

site of the United Nations 2020 World Population and Housing Census Programme are

intended to provide, in tabular form, the most important census information needed as

a basis for programmes of economic and social development and to be used for research

purposes. ey do not in any way represent all of the tabulations that a given country may

publish and certainly not all of the tabulations that may eventually be prepared for special

purposes. e tabulations do not take into account the form in which information may be

entered into a database, which may be more detailed than that required for these illustrative

census tabulations.

3.309. A major goal of these recommendations is to provide a set of tabulations that need

to be produced at the lowest geographic level pertaining to the same point in time so that a

country or area is able to meet its data needs for evidence-based socioeconomic development

planning and monitoring. While the majority of national statistical authorities use a popula

tion and housing census as the single most comprehensive vehicle to collect these necessary

statistics, others use sample surveys, registers of population and vital events, and other admin

istrative sources or a combination of these methods to derive them.

3.310. ree categories of tabulations are described below: (a) basic or essential, (b) recom

mended, and (c) optimum tabulations.

Principles and Recommendations for Population and Housing Censuses, Revision 3138

Basic or essential tabulations

3.311. ese are tabulations that are deemed of top priority for production by countries. ey

are also regarded as essential for countries in diﬃcult circumstances, such as those that have

emerged from a conﬂict or those that have not carried out a census in a long time, in terms

of providing minimum statistics to meet their basic data needs.

3.312. e set of basic or essential tabulations on population and on housing characteristics

are listed on the website of the United Nations 2020 World Population and Housing Census

Programme. e tabulations include elaborate classiﬁcations as well as relevant metadata for

each of the tabulations.

Recommended tabulations

3.313. Recommended tabulations are those that are considered adequate for meeting the

essential data needs for evidence-based planning, monitoring and implementation of national

policies because of their perceived relevance at both the national and the international levels.

ese tabulations are also designed with the potential for producing statistics at the lowest

geographic level and are expected to be produced by each country at least once in the 2020

census decade.

3.314. e recommended set of tabulations also includes the basic or essential tabula

tions discussed above. Schematic presentations of all tabulations are presented online at the

United Nations 2020 World Population and Housing Census Programme.

3.315. Associated with the recommended tabulations are the core topics that go into their

production. Core topics are therefore the main variables for the recommended tabulations.

ere are 31 core topics on population with 25 of them direct topics and 6 indirect (for a

more detailed discussion of direct and indirect topics, see paragraph 4.19).

3.316. As stated in paragraph 4.1, the aim of the recommended tabulations is to permit

national and international comparability of data due to use of common concepts and deﬁ

nitions of the core topics. For each of the recommended tabulations, the core topics that it

represents are listed as part of the metadata. Other metadata that are presented for each of

the recommended tabulations include (a) the source of statistics, that is to say, whether from

a traditional census, register-based census, survey or rolling survey; (b) the type of population

count, that is to say, whether a de jure or de facto population or a combination of these; and

Optimum tabulations

3.317. e optimum set of tabulations includes the basic or essential and the recommended

tabulations discussed above, as well as additional tabulations, and is designed to meet the

needs of most of the users at the national and the international levels. is set can be viewed

as being equivalent to the complete set of tabulations that could be generated from a popula

tion and housing census.

3.318. In order to avoid producing census tabulations that are overly voluminous or that

contain a large number of empty cells, some countries may ﬁnd it necessary to employ a more

restricted geographic classiﬁcation than what is suggested in the illustrations. For example,

basic facilities such as piped water or electricity may be almost completely lacking for large

areas of some countries. Under these circumstances, tabulation of the relevant data for small

geographic areas would not be appropriate. e geographic classiﬁcation to be utilized needs

to be carefully considered, taking into account the type of information being tabulated, its

probable frequency distribution and the uses to which the data are likely to be put. Privacy

and conﬁdentiality of individuals and households must at all times be protected (paragraphs

3.285-3.289, 3.262, 3.394).

139Census operation activities 139

3.319. Some countries may also collect data on additional topics in the census question-

naire to address speciﬁc concerns, for example, whether or not the birth of an individual is

registered, the age a woman ﬁrst marries, or vocational and technical skills. In other cases,

detailed tabulations for special populations may be required for use in planning or evaluation

of programmes. Tabulations for the non-core topics may be done after the basic tabulations

are completed. is should be based on user needs. Consequently, consultations with user

groups at both the national and local levels may be helpful in determining the most suitable

tabulation plan and method of dissemination.

(b) Thematic statistical or analytical reports

3.320. Many countries prepare diﬀerent types of thematic or analytical reports. ese reports

must be planned and scheduled during the preparatory phase and published according to the

release calendar in order to avoid outdated reports. e reports may range from volumes pre

senting extensive and detailed statistical tabulations, particularly cross-tabulations, to more

analytical reports that combine tabular materials with some interpretative or analytical text.

is latter group of reports might include, for example, volumes of regional analysis on such

subjects as population or housing conditions of urban areas, major metropolitan areas or

big cities, and regional distributions; locality reports on infrastructure; and comparisons of

key social indicators such as education, living arrangements, housing conditions, sanitation

and economic activities. Other such reports might include community proﬁle analysis of,

for example, the indigenous population, and proﬁles of speciﬁc population groups, such as

families, children, youths, persons with disabilities and older persons. Reports on popula

tion growth and distribution that examine changes in the demographic characteristics of the

country’s population with breakdowns by two or three levels of administrative areas would be

very useful. Such reports might focus on the growth, location and mobility of the population

at the national and regional levels, and administrative areas. It should be pointed out that it

is important that appropriate language is used to correspond to the target audience for each

thematic report. It is recommended that multidisciplinary task teams be established, includ

ing line ministries and agencies, for the preparation of thematic and analytical reports in line

with agreed guidelines. Partnership and external cooperation with academic institutions and

other specialists in subject matter, which can facilitate such work and strengthen collabora

tions, may be sought whenever possible.

3.321. ematic and analytical reports must be based on user needs and respond to a country’s

speciﬁc development needs and emerging issues. ese reports can also be used to show time

series and trend analyses of socioeconomic and demographic indicators and may combine

census data with other data sources to provide a more comprehensive and current outlook.

3.322. Other published reports may include the census methodology, encompassing, if appli

cable, sampling design and methodology and a census evaluation report, which may include

estimates of census coverage and the methodology used for their preparation.

3.323. It is important that users of census products be provided on a timely basis with as

much relevant information regarding the census as possible. A publication that contains

information on all types of products that will be available following the census is very use

ful to users. A brief description of each product should be provided including the estimated

timing of release, the level of geographic detail that each product carries and, for products

released periodically, the frequency of release. In the case of large census operations, several

such documents tailored to the needs of diﬀerent sets of users (for example, users in education,

health or local government) may be useful.

Principles and Recommendations for Population and Housing Censuses, Revision 3140

3.324. Many countries publish a census dictionary, which contains comprehensive deﬁni-

tions of terms and concepts and detailed classiﬁcations used to present census outputs. Some

countries also publish geographic classiﬁcations and codes, and the deﬁnitions of areas used

in the census and their relationships with the administrative areas. Explanations of user-

deﬁned areas for speciﬁc census tabulations and the type of format available (printed or

electronic) may be provided.

(d) Administrative report

3.325. One of the most important reports in the publication programme is the administrative

report, which is a record of the entire census undertaking, including problems encountered

and their solutions (see also paragraphs 3.468-3.472 on systematic recording and documenta

tion of the census experience). e report may include the following topics: a brief history of

the census in the country and the legal basis for conducting the census; budget requirements,

expenditure and control; source and allotment of funding; census committees and their

activities; stakeholder management; census organization and personnel structure; staﬀ man

agement; quality control procedures; census calendar; census cartographic work; development

and design of the questionnaires; enumeration methodology; census promotion, publicity and

communication; ﬁeld organization; manual editing and coding; data-processing develop

ment and organization; data capture; computer editing and imputation procedure; capital,

equipment and infrastructure management; computer hardware and software used; cen

sus evaluation; publication and data dissemination programme; and archiving. e census

administrative report is very useful both for the users and for the census organization itself.

e administrative report is an essential product for the planning of future censuses (see also

paragraphs 3.471-3.472).

3.326. With developments in information technology, the census data ﬁles and publications

have become increasingly available in electronic formats. A description of the procedure in the

development of these data ﬁles may also be included in the procedural report. Consideration

of a separate volume of the procedural report for the processing and dissemination phases

may be considered to ensure the completion of the planning and ﬁeld operations phases

immediately after the census enumeration.

3. Databases

3.327. In order to expand the life and usability of the data, and as a complement to the

standard production of tables, national statistical oﬃces are encouraged to store the census

data in various computerized database forms so as to better satisfy the full range of needs of

internal and external data users. Census databases assist data users by providing easy access

to a wide range of census data.

3.328. e establishment of such databases can enhance the dissemination of the census

results as well as increase their usefulness by combining census data together with related

information from other demographic enquiries in a common format. (An important special

case is bringing together the data from prior censuses into a single database.) In addition, such

databases can improve the coherence of the input and output processing systems.

3.329. Needs vary widely from user to user according to speciﬁc interests and circumstances.

ere is therefore no preferred approach to setting up a census or population database. For

example, a basic decision must be made whether to provide microdata, aggregated data or

both. Other basic design issues to be considered include whether an eﬀort is to be made

to incorporate the new census results in an existing database structure or whether one or

more new census databases are to be established, and if the latter is the case, whether the

141Census operation activities 141

new database(s) will be exclusively in the form of a census database or constitute instead the

nucleus of one or more population databases incorporating data from other sources. Consid

eration will also have to be given to such issues as identiﬁcation of the diﬀerent types of users,

their information requirements, types of information to be stored in the database, sources of

information, maintenance and update of information, processing of user queries, identiﬁca

tion of the appropriate commercial software or, alternatively, whether it is feasible to develop

such software, and selection of the appropriate hardware capable of supporting the current

database and its anticipated growth.

3.330. Since building a census or population database requires careful planning and can be

time-consuming, such implementation should ﬁt within the global statistical framework of

the organization, and be seen as an ongoing process both complementing the data dissemina

tion strategy and strengthening the statistical capacity of the organization.

(a) Microdatabase

3.331. Microdata (records of individual persons and households) collected in the census can

be stored either in their raw form, or in their ﬁnal edited form, or in a ﬁle that combines both

raw and edited records. To limit problems of conservation, the data should be stored prefer

ably on a medium of excellent reliability such as, currently, compact disk read-only memory

(CD-ROM) or a digital versatile disk read-only memory (DVD-ROM), which has much

more capacity than a CD-ROM, or a universal serial bus (USB) ﬂash drive, which provides

even more storage space. New technologies for mass storage are constantly evolving. Such new

technologies present two issues for census managers and technicians: (a) the issue of when

it will be appropriate to adopt a new technology as the standard; and (b) that of the need to

convert materials stored in older media to the new standard or otherwise provide accessibility

to the older materials.

3.332. With technological advances in mass storage devices and media, it is now feasible

to store the full census data ﬁle (one character per byte) as a single large rectangular ﬁle.

After adding a data dictionary that describes the data format and a tabulation module, one

obtains a set that could be described as a census database. e microdatabase requires a

cross-tabulation program, which can be either part of the package or external. e software

normally used for census tabulation still requires some prior training and may be confusing

to inexperienced users. More intuitive tabulation software is available, but may be either too

slow in processing or too limited in its options to be fully satisfactory.

3.333. e organization of the microdatabase may take several formats, for example the soft

ware may allow for reorganizing the data in a transposed format (for example, one separate

ﬁle per variable). is can substantially reduce the need for storage space and increase the

speed of tabulations. However, establishing this kind of database is more complex, technically

demanding and time-consuming. ere would be advantages in storing census microdata

with standard commercial databases. is approach has the advantage that many users are

already familiar with such software, and so it is easier to ﬁnd programmers and system ana

lysts in the labour market. Even though the storage space required would be comparatively

larger, today’s market for mass storage has made available very large and fast hard disks at

much cheaper prices, and the hardware market seems to continue to follow this trend.

3.334. One of the main advantages of a microdatabase is that it permits the retrieval of data,

at least in principle, at any level of detail. Since microdata could be used to obtain informa

tion on individual persons, families, households or family enterprises, privacy concerns must

always be taken into consideration. In most countries, the use of census data to identify

individuals is prohibited by law. Moreover, the long-term reputation of the national statisti

Principles and Recommendations for Population and Housing Censuses, Revision 3142

cal authority may well be jeopardized if such disclosures occur. Full elaboration of principles

and protocols for disseminating microdata is elaborated below in paragraphs 3.376-3.391.

3.335. As presented in this subsection, there are methods (such as sampling, introduction of

random disturbances, recoding and aggregation) that can be used to make such microdata

available while still protecting individuals’ rights to privacy. All have in common the fact that

they sacriﬁce some information in order to eliminate or greatly reduce the risk of disclosure.

However, it is important that census organizations interested in disseminating microdata to

outside users should take the appropriate precautions to protect privacy and conﬁdentiality.

(b) Macrodatabase

3.336. Aggregated census data can be stored in many formats, either as the results for one

census, as a database covering more than one demographic enquiry, or in a broad database of

statistical information. Whereas microdata are saved to allow aggregations to be made that

were not programmed initially, macrodata are stored to preserve earlier aggregations, to pro

vide the broad public with readily usable information, and to prevent double work by those

who may ﬁnd that the summary data they require have already been produced.

Publication equivalents

3.337. e simplest form of what could be called a database for macrodata is a straight copy

of a publication on a computer medium, usually on an optical disk (CD-ROM or DVD-

ROM) or a ﬂash drive or on the website of the census oﬃce. A machine-readable publication-

equivalent database may have the advantage of being less expensive to prepare than its hard

copy counterpart. In addition, electronic or paper copies can be made quickly, with copying

of only part of the publication if only part is required. A disadvantage is that a user needs a

computer, and one possibly provided with compatible software, in order to have access to the

census information.

3.338. e original printed publication can be captured on the computer medium by

(a) exporting the camera-ready output to some portable ﬁle formats or scanning the printed

pages, which generates raster-type images; or (b) copying the original computer ﬁles in Ameri

can Standard Code for Information Interchange (ASCII) text form and worksheet or data-

base formats. e former approach makes it extremely simple to retain all the formatting and

to include graphs and other illustrations. e latter solution has the big advantage of allowing

the user to process the information further by computer without having to re-enter the data.

is, as noted before, economizes eﬀort and prevents transcription errors. e information

content in this case is usually limited to tables, perhaps with some explanatory texts. Because

of the important advantages of each of these storage methods, census organizations can use

both. e user receives a computer medium holding the camera-ready output ﬁle or the

scanned images as well as ASCII ﬁles of the tables. If tabulated data are provided in readable

format, they may also be organized with some kind of data-browsing software. In this case,

the software should always allow for downloading in a variety of non-proprietary and popular

spreadsheet formats. is is possible especially when the medium has a large capacity.

Table-oriented databases

3.339. More advanced users may prefer that a census database of macrodata oﬀer more than

an equivalent of the printed publication. ey might like to be able to manipulate the tables

in various ways in order to obtain views or results that represent their speciﬁc requirements

more precisely. Associated graphing and thematic mapping capabilities may also be welcome.

Several statistical oﬃces have successfully ﬁlled this need. However, a major problem often

encountered is that there is no generally accepted deﬁnition of what constitutes a statistical

table and of the rules that should be followed when designing one.

143Census operation activities 143

3.340. In a controlled environment, such as that of a given census or national statistical

organization, it is possible to standardize table deﬁnitions. e most common way is to design

a basic layout having a number of attributes that together fully describe a table. Appropriate

software will then give users access to a number of operations that process the table or several

tables at the same time. Examples of such operations are reclassifying a variable (for example,

from 1-year to 5-year age groups), eliminating a dimension from a multidimensional table or

joining tables that have a dimension in common.

3.341. e availability of a standard table description language oﬀers important advantages

in exchanging tables as data-processing objects among national and international organiza

tions. However, as mentioned before, some statistical tables are not easily pressed into the

mould provided by formal descriptions. In this respect, it should be noted that statistical

tables have little in common with the structures known as relational tables in popular data

base management systems.

3.342. Nevertheless, census oﬃces should be aware of the potential oﬀered by extensible

markup language (XML). XML is not, as a matter of fact, a language itself, but rather a

metalanguage system designed to be used on the Internet. With XML, users can deﬁne their

own “tags” to structure the information within a document. XML thus oﬀers the potential of

precisely describing all elements composing a statistical table: title, subtitle, units of measure,

indicators, values, the time dimension and footnotes, in short the metadata. Other solutions,

such as EDI/EDIFACT (electronic data interchange for administration, commerce and trans

port), are a set of internationally agreed standards, directories and guidelines for the electronic

interchange of structured data between independent, computerized information systems.

Time series and indicator databases

3.343. Databases can also cover more than one demographic enquiry, and census results

can be integrated with various other data sets, including the results of earlier censuses. In

developing databases that are aimed at serving a heterogeneous user community, the issue

of a number of basic trade-oﬀs will have to be addressed. For example, on the one hand, the

number of variables should be kept as small as possible to make the database easy to use; on

the other hand, it should be as comprehensive as possible to address the broadest possible

requirements. A minimum data set of versatile indicators should consist of those variables that

are useful for a wide range of applications and consistently available across space and time,

and whose characteristics are clearly deﬁned. In developing such a database, not only storage

of the key indicators and variables themselves, but also the inclusion of some basic ﬁgures

(absolute numbers or basic data) as a way of standardizing the basic statistical framework, is

recommended.

3.344. It would be ideal to have a broadly accepted storage format that could improve inter

changeability between producers and users. e principal problem is that series usually con-

tain a number of descriptive attributes that have not been standardized. Metadata such as

key code, deﬁnition of the variable, periodicity, unit of measure, universe covered, number

of terms recorded, base year (for an index), adjustment applied, and so on, are required to

interpret the series properly.

3.345. In addition, various processing modules (custom made or commercial) can be

attached, allowing seasonal adjustment, interpolation and extrapolation, model building,

and adding or subtracting of series if relevant, and so on. Spreadsheet manipulation, as well

as graphing and mapping capabilities, can greatly enhance data presentation and analysis.

Principles and Recommendations for Population and Housing Censuses, Revision 3144

3.346. By having associated graphing and mapping capabilities, databases will greatly

increase their usefulness. Ideally users should be able to generate the graphs or maps required

by themselves and then print or plot them, paste them into a report or make the images

available for other uses.

3.3 47. Many users want data for relatively small areas concerning such matters as home

ownership, educational proﬁles and the labour market. While the database may be for one

census, some historical information can be included to allow users to observe prevailing

trends over time.

3.348. Both microdata and macrodata can be at the basis of these dissemination products.

However, owing to disclosure problems as well as in order to increase processing speed, some

form of prior aggregation is usually applied, for example by using summary data. Such sum

mary data could also be combined with the general purpose graphing and mapping software.

However, this would result in a reduction of the user community to those able to handle

rather more complicated processing jobs. Making available a census database with tightly

integrated graphing and mapping capabilities (which usually implies a tabulation function)

is an excellent way to improve the eﬀectiveness of census information dissemination. If it is

to be commercially successful, the product must be easy to use.

4. Geographic products

(a) Basic maps

3.349. Census oﬃces should take advantage of emerging GIS technologies to make the cen

sus results more understandable and easier to use. e purpose of statistical maps is to present

the results in terms of their geographic distribution and also to make it easier for the general

public to understand census results than when information is presented only in the form of

statistical tables. ere is special interest in the current pattern of geographic distribution and

also in changes in patterns that have occurred over time, particularly since the last census.

Harmonization of the boundaries between the censuses is essential for comparability of data.

3.350. e provision of maps serves two purposes: ﬁrst, census area identiﬁcation maps locate

and show the boundaries of all administrative areas and units for which data are reported in

census publications; and second, statistical or thematic maps and graphs present the signiﬁ

cant results of the census, thus allowing the general user to visualize the geographic distribu-

tions and patterns inherent in the data. Well-designed and attractive maps will interest the

users of census reports, and may raise questions that send them to the statistical tables for

further details.

3.351. ere are three major types of area identiﬁcation maps that are commonly used in

most census publications in printed or GIS shapeﬁle formats: (a) national maps showing

the boundaries of the ﬁrst- and second-order geographic divisions and of the major cities

or metropolitan areas; (b) maps of each ﬁrst-order division showing the boundaries of the

second- and third-order divisions for which statistical tables will be prepared; and (c) urban

or metropolitan maps showing small sub-area boundaries as well as general streets, roads

and rivers.

(b) Thematic maps

3.352. A comprehensive map publication programme should be developed as part of the

overall population and housing census publication programme so that the needed resources

may be provided within the budget at the initial planning stages. In addition to preparing

145Census operation activities 145

maps for census tables and reports, many countries have also found it useful to produce a

population atlas as a census output. Collaboration with other departments and interested

agencies might be sought to facilitate the production of an atlas volume. e atlas would

include maps depicting population and housing characteristics, as well as other data inﬂu

encing the growth, composition and distribution pattern of population and housing (see

paragraphs 3.83-3.93).

3.353. As regards thematic maps, priority indicators for a population and housing census

are total population and its distribution by sub-area, population density, urban and rural

population or metropolitan and non-metropolitan population, and changes in the population

totals since the last census. Other important indicators include age, sex, fertility, mortality,

migration, educational attainment, employment, household size, type of housing, ownership,

number of rooms and sanitary facilities, with a growing demand also for data on commu

nication (telephones, television, computers and Internet access), transport (vehicles), a broad

range of household amenities, and recently also population-based development indicators

such as household access to safe water, household waste management and multiple sources of

household incomes, such as the incidence of remittances. is list of indicators is merely an

illustration of the type of thematic maps individual countries might ﬁnd useful to produce.

Producing maps using the same set of indicators enables countries to meaningfully compare

their results over time and with international or regional norms.

3.354. Maps are an invaluable aid in meaningfully comparing subnational results with

national values or with other international and regional norms. Emerging technologies pro

vide great ﬂexibility in composing informative and visually appealing maps. Often several

maps can be combined on a single page to show one indicator, for example, for urban and

rural populations. Also, combining maps and statistical charts is an eﬀective means of pre

senting census information.

3.355. By having associated graphing and mapping capabilities, databases will greatly

increase their usefulness. Ideally users should be able to generate the graphs or maps for their

own needs. Several census organizations have produced this kind of product, sometimes in

cooperation with a commercial company. However, it is recommended that census oﬃces

develop mapping capabilities as a core competence for statistical production. Many users

require small-area data concerning such matters as home ownership, educational proﬁles,

the labour market, and so on. While the database may be for one census, some historical

information can be included to allow users to observe prevailing trends over time. As with all

time-series-type data, it is important to maintain consistency in both deﬁnition and spatial

representations to ensure comparability.

3.356. Both microdata and macrodata can be at the basis of these dissemination products.

However, owing to the need to maintain conﬁdentiality, and in order to increase processing

speed, some form of prior aggregation is usually applied, for example by using summary data.

Such summary data could also be combined with the general purpose graphing and map

ping software. Making available a census database with codes and names matching the GIS

shapeﬁles with tightly integrated graphing and mapping capabilities (which usually implies

a tabulation function) is an excellent way to improve the eﬀectiveness of census information

dissemination.

3.357. e following list presents some suggested topics for census maps. e list is not

exhaustive: most topics that appear in the questionnaire as well as derived topics covered in

part two can be presented in cartographic form. In some countries, special topics such as

population distribution by ethnic or language group may be appropriate. Conversely, some of

the listed maps present information on the same topic in somewhat diﬀerent form, so that a

statistical agency may wish to select the most suitable indicator for the needs of the country.

Principles and Recommendations for Population and Housing Censuses, Revision 3146

Illustrative list of thematic census maps

• Population dynamics and distribution

— Percentage population change during intercensal period(s)

— Average annual growth rate

— Population density (persons per square kilometre)

— Urban population as percentage of total population

— Distribution and size of major cities and towns

— In-migration, out-migration and net migration rates

— Born in country and foreign born

— Born in another division of the country

• Demographic characteristics

— Sex ratio (males per 100 females), possibly by age groups

— Percentage of population aged 0-14

— Percentage of population aged 15-64

— Percentage of population aged 65 and over

— Percentage female population of childbearing ages 15-49

— Total dependency ratio (population aged 0-14 and 65 and over, as percentage

of population aged 15-64)

— Marital status

— Birth rate

— Total fertility rate

— Mean age at ﬁrst marriage

— Death rate

— Infant mortality rate

— Life expectancy at birth

— Percentage of persons with disabilities

• Socioeconomic characteristics

— Percentage of children not in primary school

— Adult literacy rate (aged 15 and over)

— Mean years of schooling (aged 25 and over)

— Illiteracy rate of population aged 15 and over

— Illiterate population aged 15 and over (total number)

— Educational level of population aged 10 and over

— Labour force as percentage of total population

— Women’s share of adult labour force

— Percentage of labour force by economic sector, type of occupation and status

in employment

— Poverty mapping

• Households and housing

— Average number of persons per household

— Percentage of households headed by women

— Average number of dwelling rooms per household

147Census operation activities 147

— Tenure status (owned, rented, and so forth)

— Type of construction material

— Percentage of population with access to adequate shelter

— Percentage of population with access to safe water

— Percentage of population with access to electricity

— Percentage of population with access to sanitation

— Percentage of population with access to health services

3.358. Where appropriate, the indicators can be presented disaggregated by gender as well

as by urban or rural area (for example, where the rural population is greater than about

25 per cent of the total population). If information about an indicator is also available from

a previous census, it is often very informative to produce change maps or to present maps for

both time periods.

3.359. Also where appropriate, countries are encouraged to perform spatial statistical analysis

by producing maps showing spatial clustering and outlier analysis of the variables of interest,

such as electricity and water.

3.360. e development of locality (village, town, city, community, small area) population size

maps by region is of particular value. ese maps combine two types of information: locality

population statistics and locality locations in each region or subnational area. More informa

tion can be presented on, for example, the locality location within the district and the region,

habitable and non-habitable areas, densely populated localities, areas with no localities, and the

proximity of localities. Locality population size maps can also be used as base maps for addi

tional information on locality services and activities, and on location and distribution of locali-

ties without speciﬁc services, such as primary schools, dispensaries, piped water, and so forth.

3.361. Geographic information systems embody hardware and software conﬁgurations

designed to support the capture, management, analysis and dissemination of spatially refer

enced data. Applied to census activities and outputs, such systems facilitate census cartog-

raphy and data capture, and by linking population data (demographic, social and socioeco-

nomic) to geographic areas, GIS provides very powerful data management functionalities in

allowing users to explore, analyse, describe and communicate population census information

according to their own data and information demands.

3.362. In practical terms, such systems may range from simple desktop mapping facilities

to complete GIS systems capable of solving complex planning and management problems,

producing detailed georeferenced inventories and spatial statistical analysis. e ability to use

space to integrate and manipulate data sets from heterogeneous sources can make its applica

tion relevant to planning and managing the census process itself. For example, GIS provides

functions for the aerial interpolation of statistical data in cases where the boundaries of aerial

units have changed between censuses.

3.363. Geospatial analysis must become a core competence in any census oﬃce.

3.364. Statistical oﬃces should develop GIS applications with population data and other geo

referenced data from other sources for more advanced forms of spatial analysis. e role of the

census oﬃce should be to supply census data at the right level and in the right format to users.

Census oﬃces provide vital information on current demographic conditions and future trends

for policymakers in a range of sectors, such as health care, education, infrastructure planning,

agriculture and natural resources management; and the provision of spatially referenced census

databases is a prerequisite of the facilitation of the use of demographic data in these ﬁelds.

Principles and Recommendations for Population and Housing Censuses, Revision 3148

3.365. To achieve maximum eﬃciency gains, GIS applications should also be capable of

generating additional geographic information beyond those used in the census, such as school

and health districts, water and other biophysical catchment areas, and power and utility

service units. ese entities will have to be constructed from the smallest geographically

identiﬁed units available in the census, such as census blocks, grid squares or enumeration

areas. If, as is the case in most developing countries, enumeration areas are the smallest units,

this will have important implications for the establishment of enumeration area boundaries.

is requires close collaboration between national statistical organizations and national map

ping and survey agencies on the one side, and school, health, water and power authorities

on the other, when enumeration area boundaries are drawn or modiﬁed, to avoid potential

discrepancies later on.

3.366. Apart from providing national statistical organizations with a very eﬀective means to

disseminate and increase the utilization of census data, GIS, more than any other data man

agement system, provide easy and user-friendly access to census data in user-relevant formats.

is allows analysts and planners to undertake policy analysis, planning and research that can

more readily identify thematic and geographic priority areas and thus contribute to evidence-

based and better-informed policy and decision-making at diﬀerent levels of geography. Some

of the spatial statistical analysis includes clustering, Moran’s spatial autocorrelation, Anselin

outlier analysis, Getis-Ord hotspot analysis, ordinary least squares regression and geographi

cally weighted regression. It allows governments to eﬀectively monitor development progress

across diﬀerent sectors at village, municipality and subregional levels; it raises awareness about

the importance of census and other socioeconomic data; and it increases the institutional

capacity of national statistical oﬃces and social and economic planning agencies to engage

in more in-depth analyses of social and economic data and deliver information products in

even more user-friendly formats.

5. Interactive electronic outputs

3.367. It is of paramount importance that census data and information produced are widely

disseminated and communicated, and that national statistical and census oﬃces involved

in this process have a pronounced customer, client and stakeholder focus. at means that

national statistical and census oﬃces should place more emphasis on providing a service and

creating partnerships than on merely providing products, and should be guided by user-

relevance and user-friendliness in all their operations, rather than by tradition in producing

the tables, graphs and reports that they have always produced.

3.368. Given its importance and widespread use, the web has emerged as the primary means

of providing general access to census statistics. Many national statistical and census oﬃces

have utilized the Internet as the principal channel for data communication, positioning their

websites into comprehensive census data repositories, enabling users to have access to all

published data online. When developing new census products, and when reviewing existing

products, national statistical and census oﬃces should consider all ways and means of making

census statistics accessible, giving high priority to dissemination on the web. e advantages

of online dissemination are primarily in terms of speed, ﬂexibility and cost, as well as in pro

viding accessibility to census results to a wide range of data users and allowing the delivery

of data to be tailored to the level of sophistication of the user.

3.369. Making a census database available online along with integrated searching, tabulat

ing, graphing, mapping and analysis capabilities is an important way to improve the eﬀective-

ness of census data dissemination. Most national statistical and census oﬃces provide user

access to electronic databases and data ﬁles through their websites, satisfying the full range

of needs of internal and external data users. is is a valuable service that allows users to

149Census operation activities 149

access and display census data instantaneously and interactively. e establishment of such

databases can enhance the dissemination of census results as well as increase their usefulness

by allowing user interaction with census data. User interaction is a key concept whereby users

are enabled and empowered to access and explore census data themselves, and build their own

customized tables or spatially conﬁgure data outputs according to their own requirements.

3.370. Interactive web-based data tools provide a user-friendly entry point to the entire range

of census outputs disseminated by national statistical and census oﬃces. Basic design con

siderations of web-based interactive tools should factor issues such as identiﬁcation of the

diﬀerent types of users, their information requirements and the types of information to be

stored in the database. Content should be organized so that it can be easily understood and

found, with an overview given to provide orienting information to users about the data that

can be accessed using the interface. Context should always be provided to all outputs through

metadata, links to related information, and cross-referencing to glossaries, publications and

other background material.

3.371. In practical terms, interactive web-based data tools should enable users to access cen

sus data themselves, and build their own customized tables or spatially conﬁgure data outputs

according to varying requirements. e tools should allow users to visualize and explore the

data in column charts, line graphs, maps and scatterplots. e table-building functionality

should also have the ability to sort and order tabular results, and more easily select survey

years and indicators. Tools should also be provided for downloading, conducting analysis or

retrieval for use in other software. Design considerations to improve the interactivity of data

interfaces should include the provision of user support. It is highly recommended to help

users to anticipate, interpret and evaluate results. Support to users should include demonstra

tions and tutorials intended to describe how to perform the various functions related to the

interactive web-based tools.

3.372. In addition to the Internet, interactive electronic products can also be accessed

through other media, including CD-ROM, DVD and ﬂash drive.

6. Microdata dissemination

(a) Deﬁnition of microdata

3.373. In general, when statistical agencies or other data producers conduct surveys or cen

suses or collect administrative data, they gather information from each unit of observation.

Such a unit can be a household, a person, a ﬁrm or enterprise, an agricultural holding, a

school, a health facility or other. In this context, microdata are the electronic data ﬁles con

taining information about each unit of observation. Microdata are thus opposed to macrodata

or aggregated data, which provide a summarized version of this information in the form of

means, ratios, frequencies or other summary statistics.

3.374. Typically, microdata are organized in data ﬁles in which each line (or record) contains

information about one unit of observation. is information is stored in variables. Variables

can be of diﬀerent types (for example, numerical or alphanumerical, discrete or continuous).

ey can be obtained directly from the respondent via a questionnaire or by observation or

measurement (for example, by GPS positioning), or imputed or calculated.

3.375. In the context of the population and housing census, microdata refer to electronic ﬁles

consisting of individual records on persons, households and housing units. More speciﬁcally,

microdata would typically be organized in multiple ﬁles: one with records on households,

another with records on individuals, and yet another with records on housing units.

The elaboration on the dis-

semination of microdata is

largely based on Olivier Dupriez

and Ernie Boyko, Dissemination

of Microdata Files: Principles,

Procedures and Practices, IHSN

Working Paper No. 005 (2010).

Principles and Recommendations for Population and Housing Censuses, Revision 3150

(b) Core principles for disseminating census microdata

3.376. e United Nations Fundamental Principles of Oﬃcial Statistics

provide unam-

biguous guidance in administering oﬃcial statistics at national and international levels.

A particular emphasis of these principles is on conﬁdentiality of information collected for

statistical purposes. e sixth principle, governing international statistical activities, states:

“Individual data collected by statistical agencies for statistical compilation, whether or not

they refer to natural or legal persons, are to be strictly conﬁdential and used exclusively for

statistical purposes.”

3.377. Any principles for microdata access must be consistent with this recommended prin-

ciple and the principles contained in the legislation pertaining to the national statistical

authority. e following principles should be considered for managing the conﬁdentiality

of microdata:

Principle 1: Appropriate use of microdata

3.378. It is appropriate for microdata collected for oﬃcial statistical purposes to be used for

statistical analysis to support research as long as conﬁdentiality is protected.

3.379. Making available microdata for research is not in contradiction with the sixth

United Nations Fundamental Principle as long as it is not possible to identify data referring

to an individual. Principle 1 does not constitute an obligation to provide microdata. e

national statistical oﬃce should be the one to decide whether to provide microdata or not.

ere may be other concerns (for example, quality) that make it inappropriate to provide

access to microdata. Or there may be speciﬁc persons or institutions to whom it would be

inappropriate to provide microdata.

Principle 2: Microdata should only be made available for statistical purposes

3.380. For principle 2, a distinction has to be made between statistical or analytical uses and

administrative uses. In the case of statistical or analytical use, the aim is to derive statistics

that refer to a group (be it of persons or legal entities). In the case of administrative use, the

aim is to derive information about a particular person or legal entity to make a decision that

may bring beneﬁt or harm to the individual. For example, some requests for data may be legal

(a court order) but inconsistent with this principle. It is in the interest of public conﬁdence

in the oﬃcial statistical system that these requests are refused. If the use of the microdata

is incompatible with statistical or analytical purposes, then microdata access should not be

provided. Ethics committees or a similar arrangement may assist in situations where there is

uncertainty whether to provide access or not.

3.381. Researchers are accessing microdata for research purposes, but to support this research

they may need to compile statistical aggregations of various forms, compile statistical distri

butions, ﬁt statistical models or analyse statistical diﬀerences between subpopulations. ese

uses would be consistent with statistical purposes. To the extent that this is how the microdata

are being used, it could also be said to support research purposes.

Principle 3: Provision of microdata should be consistent with legal and other necessary

arrangements that ensure that conﬁdentiality of the released microdata is protected

3.382. With respect to principle 3, legal arrangements to protect conﬁdentiality should be in

place before any microdata are released. However, the legal arrangements have to be comple

mented with administrative and technical measures to regulate the access to microdata and to

ensure that individual data cannot be disclosed. e existence and visibility of such arrange

ments (whether in law or supplementary regulations, ordinances, and so forth) are necessary

to increase public conﬁdence that microdata will be used appropriately. Legal arrangements

The elaboration of core

principles for dissemination of

microdata is quoted from Man-

aging Statistical Conﬁdentiality

and Microdata Access: Principles

and Guidelines of Good Practice

(United Nations publication,

Sales No. E.07.II.E.7).

Presented at the United Nations

Statistics Division website at:

http://unstats.un.org/unsd/dnss

/gp/fundprinciples.aspx.

Ibid.

151Census operation activities 151

are clearly preferable, but in some countries this may not be possible, and some other form of

administrative arrangements should be put in place. e legal (or other arrangements) should

also be cleared with the privacy authorities of countries where they exist before they are estab

lished by law. If such authorities do not exist, there may be non-governmental organizations

that have a “watchdog” role on privacy matters. It would be sensible to get their support for

any legal or other arrangements, or at least to address any serious concerns they might have.

In some countries, authorizing legislation does not exist. At a minimum, release of micro

data should be supported by some form of authority. However, an authorizing legislation is

a preferable approach.

Principle 4: The procedures for researcher access to microdata, as well as the uses and users

of microdata, should be transparent and publicly available

3.383. Principle 4 is important to increase public conﬁdence that microdata are being used

appropriately and to show that decisions about microdata release are taken on an objective

basis. It is up to the national statistical authority to decide whether, how and to whom micro

data can be released. But their decisions should be transparent. e website of the national

statistical authority is an eﬀective way of ensuring compliance and also for providing informa

tion on how to access research reports based on released microdata.

3.384. When disseminating census microdata ﬁles to the public, researchers or other agen-

cies, the national statistical authority faces a conﬂicting mission. On the one hand, it aims

to release microdata ﬁles supporting a wide range of statistical analyses; on the other, it

must safeguard the conﬁdentiality of respondents’ identities. Processes aimed at the latter are

referred to collectively as statistical disclosure control or anonymization.

3.385. A disclosure occurs when a person or organization recognizes or learns via released

data something they did not know about another person. ere are two types of disclosure

risk: identity disclosure and attribute disclosure.

e former occurs when a respondent’s

identity is directly associated with a disseminated data record. is can occur easily when

the data record includes variables unambiguously identifying the respondent—for instance,

the respondent’s name, address, passport or identiﬁcation number, or telephone number. It

is essential that such identifying variables be removed from any microdata ﬁles before dis

semination. Attribute disclosure occurs when attribute values (or estimates thereof) in the

disseminated data are associated with a particular respondent.

3.386. A combination of variables in a microdata record that can be applied to reidentify a

respondent is referred to as a “key”. Reidentiﬁcation can occur (a) when a respondent is rare

in the population with respect to a certain key value; and (b) when this key can be used to

match a microdata ﬁle to other data ﬁles that might contain direct or other identiﬁers such as

voter lists, land registers or school records (or even publicly accessible Internet search engines).

3.387. e essential component of dissemination of census microdata ﬁles is avoiding both

identity and attribute disclosures. In that respect, there is a need to strictly apply statistical

disclosure control or anonymization techniques for census microdata ﬁles. e ﬁrst key step

in anonymizing a microdata ﬁle is to remove all direct identiﬁers—variables that unambigu

ously identify the respondent. ereafter, a microdata ﬁle can be anonymized further by

applying statistical disclosure control techniques.

(d) Protocols for dissemination of census microdata

3.388. Disseminating census microdata may be an unprecedented activity for the national

statistical authority. In that context, there is a need to develop particular protocols that

The elaboration of procedures

for anonymizing microdata

draws extensively from Anco

Hundepool, Josep Dominho-

Ferrer, Luisa Franconi, Sarah

Giessing, Rainer Lenz, Jane

Longhurst, Eric Schulte Nordholt,

Giovanni Seri, Peter-Paul de Wolf,

Handbook on Statistical Disclosure

Control, Version 1.0 (Centre of

Excellence for Statistical Disclo-

sure Control, 2006).

Diane Lambert, “Measures of Dis-

closure Risk and Harm”, Journal

of Oﬃcial Statistics vol. 9, No. 2

(Statistics Sweden, 1993).

For full elaboration of these tech-

niques, refer to Olivier Dupriez

and Ernie Boyko, Dissemination

of Microdata Files: Principles,

Procedures and Practices, IHSN

Working Paper No. 005 (2010),

chapter 7.

Principles and Recommendations for Population and Housing Censuses, Revision 3152

would comply with the essential principles for disseminating microdata, as described above,

and would also spell out the necessary requirements and components of such dissemination.

Hence, such a protocol would need to take into account the following components and

requirements:

• Openness. Access on equal terms for the research community at the lowest pos-

sible cost, preferably at no more than the marginal cost of dissemination.

• Flexibility. Taking into account the rapid and often unpredictable changes in

information technologies, the characteristics of each research ﬁeld and the diver

sity of research systems, legal systems and cultures of each member country.

• Transparency. Information on research data and data-producing organizations,

documentation on the data and speciﬁcations of conditions attached to the use

of these data should be internationally available in a transparent way, ideally

through the Internet.

• Legal conformity. Data access arrangements should respect the legal rights and

legitimate interests of all stakeholders.

• Protection of intellectual property. Data access arrangements should consider

the applicability of copyright or of other intellectual property laws that may be

relevant to publicly funded research databases.

• Formal responsibility. Access arrangements should promote explicit, formal

institutional practices, such as the development of rules and regulations, regard

ing the responsibilities of the various parties involved in data-related activities.

ese practices should pertain to authorship, producer credits, ownership, dis

semination, usage restrictions, ﬁnancial arrangements, ethical rules, licensing

terms, liability and sustainable archiving.

• Professionalism. Institutional arrangements for the management of research data

should be based on the relevant professional standards and values embodied in

the codes of conduct of the scientiﬁc communities involved.

• Interoperability. Technological and semantic interoperability is a key considera

tion in enabling and promoting international and interdisciplinary access to and

use of research data.

• Quality. e value and utility of research data depend, to a large extent, on the

quality of the data. Data managers, and data collection organizations, should

pay particular attention to ensuring compliance with explicit quality standards.

• Security. Speciﬁc attention should be devoted to supporting the use of techniques

and instruments to guarantee the integrity and security of data.

• Eﬃciency. One of the central goals of promoting data access and sharing is to

improve the overall eﬃciency of publicly funded data collection to avoid the

expensive and unnecessary duplication of data collection eﬀorts.

• Accountability. e performance of data access arrangements should be subject

to periodic evaluation by user groups, responsible institutions and funding agen

cies.

• Sustainability. Due consideration should be given to the sustainability of access

to publicly funded research data as a key element of the research infrastructure.

is means taking administrative responsibility for the measures to guarantee per

manent access to data that have been determined to require long-term retention.

As presented in OECD Principles

and Guidelines for Access to

Research Data from Public Fund-

ing, Organisation for Economic

Co-operation and Development

(2007).

153Census operation activities 153

(e) Dissemination of population and housing census microdata in practice

3.389. It can be expected that the 2020 round of population and housing censuses, taking

into account the contemporary development of processing technology and power, brings con

siderable pressure on national statistical authorities in respect of dissemination of population

and housing census microdata. In the context of implementing the principles and protocols

described in the preceding paragraphs, national statistical authorities would need to ensure

such dissemination in at least two diﬀerent settings.

3.390. For the purpose of public dissemination, either online or on electronic media, only a

representative sample of the individual records should be made available after ensuring the

conﬁdentiality or non-disclosure of individual information as elaborated above. e size of the

sample would depend on the capacity and resources of the national statistical or census oﬃce.

3.391. e complete population and housing census master ﬁle should be made available

to users using the model of the data enclave. is is a facility equipped with computers not

linked to the Internet or an external network and from which no information can be down

loaded via USB ports, CD, DVD or other drives. Users interested in accessing a data enclave

will not necessarily have access to the full census data set—only to the particular data subset

they require. ey will be asked to complete an application form demonstrating a legitimate

need to access these data to fulﬁl a stated statistical or research purpose and be briefed on the

legal responsibility and repercussions related to maintaining the conﬁdentiality of individual

information. e outputs generated need to be scrutinized by way of a full disclosure review

before release and they can contain only aggregates.

7. Customized products

3.392. e increasing activity in the ﬁeld of economic and social planning and the attention

of such planning to subnational areas are placing new demands on statistical information in

general and on population and housing censuses in particular. ere is an increasing need

for tabulations and mapping not only by major and minor civil divisions and by other units

of analysis such as metropolitan areas but even, beyond these, by small local areas.

3.393. erefore, it is useful to establish an “on request” service for users who require aggre

gates not available through other means. is will be especially relevant in situations where

outsiders cannot obtain census microdatabases. In essence, the service would require that

users provide the census oﬃce with the details of the tables or other aggregates requested so

that the census oﬃce could fulﬁl the request, normally against payment of a certain compen

sation fee. Oﬀering and promoting this service, especially online, would place the statistical

service in a more desirable proactive position, rather than a static one, and could be a strong

catalyst for closer cooperation with census product users.

3.394. e cost of such special purpose tabulations, which require computer programming,

could be high, especially for academic institutions and other users who do not have access

to a large budget. Some statistical organizations allow users to do the necessary work using

user-friendly software. A clearly written manual is required to guide users in using the soft

ware, including the contents of the census data dictionary and other relevant information.

e resulting tables are checked for any possible breach of conﬁdentiality, in particular table

cells with very small values.

3.395. Many census organizations provide services for special requests for census products,

such as thematic databases, tables, and graphic and mapping outputs that can be designed

for small, medium and large businesses, communities or special interest groups. ese ser

vices are normally provided to meet the increasing demand of data users for a wide range of

Principles and Recommendations for Population and Housing Censuses, Revision 3154

applications, such as monitoring trends, analysing unmet needs, identifying market poten-

tial, segmenting markets, identifying service areas and priority zones, determining optimum

site locations, and designing and advertising new products and services. Each category of

products should also be made available on various media (namely, paper, disk, online) for

dissemination according to user requirements.

3.396. Once the databases are created and have served the policy needs, they can serve other

data users if they have market value. Since the national statistical organization is normally

the only source of many geographic databases related to census data applications, market

demand for these products is increasing, particularly in the geographic and population-related

areas. In such cases, census products could be governed by a licence. e licence permits the

users to use the product without transferring ownership, since ownership remains with the

government agency. Either of two diﬀerent licensing arrangements may be applied. e ﬁrst

is oﬀered to organizations that use the data for their own needs, and the other is oﬀered to

organizations that redistribute data or provide analytical services using census data to other

persons or organizations for a fee.

3.39 7. Customized services of data on computer media are diﬀerentiated in terms of the

forms of the data. Census products may be distributed in their original form, with or with

out other related information, or they can be distributed after making certain value-added

modiﬁcations to meet the need of the users. Examples of such value-added activities include

converting the data into another format (for use by other software packages), making the data

more useful by creating subsets of the original data sets, merging the data from other sources

and bundling with software. It is encouraged to disseminate census content in formats that

comply with the requirements assessed by the Open Knowledge Foundation.

According

to these requirements, the openness of the contents is assessed within the Open Knowledge

conceptual framework and concerns the possibility to reuse, revise, remix and redistribute

data. In cases where copyright laws protect census data ownership, some royalty fees and data

usage fees may be charged to the distributors to ensure a minimum return. However, if prices

are too high, such charges can also be a barrier to the use of the census data.

3.398. Some countries may assist their users by merging selected variables with the GIS

shapeﬁles as a customized product. is has proven to be beneﬁcial for schoolchildren.

8. General interest and special audience products

3.399. Information generated by a census is by deﬁnition of use to a wide range of users with

a variety of expertise. With the increase of demand for census products, eﬀorts must be made

by census oﬃces to produce a variety of products for various stakeholder groups, including

special interest groups. In order to address various stakeholder needs, census oﬃces must

segment stakeholders into groups to better know, understand and respond to their needs.

is will form the basis of the various census products. In response to stakeholder needs,

census oﬃces may prepare special audience products for key variables such as policy summary

reports; thematic and analytical reports; key ﬁndings reports; fact sheets; posters, brochures

and ﬂyers; basic reports; detailed tables and spreadsheets; articles; and video and social media

products. Special audience analytical or thematic reports incorporate a high level of very

sound analysis undertaken by staﬀ who have a solid foundation in analytical techniques

as well as the topic being analysed. In some cases, countries may undertake the analysis in

collaboration with academic institutions or other specialists. Criteria used in establishing

the topics chosen will have to be set by the country concerned, and may include particularly

interesting facts shown by census data (perhaps conﬁrming or rebutting conventional theo

ries; confronting census data with material from other sources; or responding to issues raised

by the public during user consultations of the collection).

See https://okfn.org/opendata.

155Census operation activities 155

3.400. It should be noted that the following products can only be eﬀective in encouraging

the use of census information if they are prepared in a timely and professional manner. is

will require specialist skills from people familiar with communicating to the target audiences.

ese resources are expensive and countries are required to adequately plan and budget for

these products and campaigns.

(a) Posters

3.401. One of the most common ways to disseminate census information consists of pub

lishing posters highlighting key facts such as: How many are we? Where do we live? and

summarizing a proﬁle for the major civil divisions of a country. Posters might also be pre

pared addressing issues relevant to special population segments: teenagers, adults, indigenous

populations, seniors and women’s groups.

3.402. Since the objective of a poster is to catch the eye at a distance, relatively few facts

should be presented so that the key message is immediately visible. Posters can be greatly

enhanced by the addition of well-designed graphs, infographics and maps to increase the

readability and comprehensibility of the key message. Posters and banners are short-term

communication products and should be used to communicate key ﬁndings.

(b) Brochures and ﬂyers

3.403. Professionally designed brochures and ﬂyers are another way to disseminate basic

census data. ese brochures should be written in a very easy and comprehensible language

indicating the demographic proﬁle of the country illustrated with suitable graphics and

explanatory material. In some countries these brochures might be addressed to speciﬁc issues

on population. ey are particularly suitable for preparation as promotional materials for

people attending events and exhibitions, such as the launch of more traditional materials, or

for inclusion on display racks in libraries of government oﬃces.

3.404. In order to create a better understanding among certain interest groups, the use of

other communication media are recommended, including videos, sketches, theatre and online

videos. In order to promote the story behind the numbers and increase the use of census data,

graphics such as charts or maps could be included on videotape, CD or DVD, or memory

sticks. ese might indicate how census data can assist policymakers, planners and people in

general with understanding their societies, and how census data can assist in identifying the

main problems and assist with evaluation of solutions.

(d) Instructional materials

3.405. Instructional materials in an easy-to-understand form can be prepared for the general

public, indicating the advantages and limitations of census data. Such material can often

form the basis of information campaigns as part of the advocacy material for the next census.

3.406. A particular implementation of instructional materials can be the preparation of a kit

for use in schools. Not only will this provide high-quality information for the students but,

by including exposure to the use of statistical materials in the school process, it will encourage

the use of evidence-based analysis throughout society. It should be noted that professional

assistance should be sought in ensuring that these materials follow sound educational prac

tices and can be accommodated within the appropriate curriculum.

Principles and Recommendations for Population and Housing Censuses, Revision 3156

(e) Social media

3.407. Internet-based social media have become an indispensable tool in disseminating infor

mation and marketing statistical products. Various social media platforms have been success-

fully used by countries as part of the dissemination of their census results. Interacting with

followers and users on these platforms provides the census organization with an opportunity

to disseminate information, build relationships with established and new users, and engage

the public on a regular basis.

3.408. Social media platforms such as Facebook, Twitter and online video sites can be used

to post all census-related advertisements and other videos.

3.409. During the build-up to the census phase, information about the upcoming census,

informing the public about what to expect when ﬁeld workers visit their homes and also the

importance of conducting a survey of this magnitude, can be disseminated using social media.

D. Census data utilization

1. General uses of population and housing censuses

3.410. Population censuses are traditionally used for public and private sector policymaking,

planning, administrative and research purposes at national and subnational level. One of the

most basic of the administrative uses of census data is in the demarcation of constituencies

and the allocation of representation on governing bodies. Certain aspects of the legal or

administrative status of territorial divisions may also depend on the size of their populations.

Housing censuses are used to develop benchmark housing statistics and to formulate hous

ing policy and programmes, and in the private sector to assist in site selection for industrial,

retail and service facilities, as well as for the commercial development of residential housing.

3.411. Information on the size, distribution and characteristics of a country’s population is

essential to describing and assessing its economic, social and demographic circumstances and

to developing sound policies and programmes aimed at fostering the welfare of a country and

its population. e population and housing census, by providing comparable basic statistics

for a country as a whole and for each administrative unit and locality therein, can make an

important contribution to the overall planning process and the management of national

development. e availability of information at the lowest levels of administrative unit is

valuable for the management and evaluation of such programmes as education and literacy,

employment and human resources, reproductive health and family planning, housing and

environment, maternal and child health, rural development, transportation and highway

planning, urbanization and welfare. Population and housing censuses are also unique sources

of data for producing relevant social indicators to monitor the impact of these government

policies and programmes (see paragraphs 3.430-3.432).

(a) Uses of population censuses

3.412. e uses of population census results and the associated tabulations described in this

volume are listed according to the topics presented in paragraph 4.21.

3.413. e total population and its distribution among major and minor territorial divisions

and localities are frequently a legal requirement of the census because these results are used

for determining the apportionment of representation in legislative bodies, for administrative

purposes and for planning the location of economic and social facilities. Internal migration,

one of the major sources of population change, frequently aﬀects the trends in population

distribution. Data on internal and international migration, together with fertility and mortal

157Census operation activities 157

ity, are needed to prepare population estimates for planning purposes and for determining

policies on migration and assessing their eﬀectiveness.

3.414. e household, a basic socioeconomic unit in all countries, is often central to the

study of social and economic development. e number, size and structure of households and

changes in the rate of household formation are useful for planning and for developing special

policies formulated for selected groups of the population, such as children, older persons and

persons with disabilities. erefore, the distribution of individuals within households is used

to determine the living arrangements of families, the patterns of family structure observed,

the time when new families are formed and changes in family structure due to death, divorce,

migration or the departure of children to form their own households. e relationship among

household members can be used to determine family structure and the existence of house

holds composed, partially or completely, of unrelated persons.

3.415. Traditionally deﬁned demographic and social characteristics collected from the popu

lation census include sex, age, marital status, religion, language and national or ethnic group.

Sex and age are fundamental to the majority of the characteristics collected in the census.

Census data provide more data than any other single source on gender diﬀerences.

3.416. Depending on national circumstances, cultural diversity may be measured by lan

guage spoken in the home or community, religion and national or ethnic group. For countries

that are not homogeneous in terms of one or more of these variables, linguistic, religious and

national or ethnic groups provide the basic information for a quantitative assessment of the

relative size and age-sex distribution of this diversity.

3.417. Although census data on fertility and mortality cannot serve as a substitute for reliable

birth and death statistics from civil registrations, they are particularly valuable for countries

where birth or death registration is lacking or incomplete and vital statistics are therefore una

vailable. Even in countries with complete registration of these events, the population census is

useful as a supplement to satisfactory registration data because the fertility questions provide

data for calculating lifetime fertility of the female population or cohort fertility.

3.418. Education has historically been one of the key factors determining the quality of life,

and interest in education continues today in most countries of the world, with emphasis on

improving access to education and the quality of education, as well as broadening the scope

of basic education.

Education is also considered a major tool in closing the gap between

women and men in respect of socioeconomic opportunities. Benchmark data obtained from

national population censuses will therefore be of considerable importance towards fulﬁll

ing this objective. Census data reveal the disparity in educational opportunities between the

sexes, age cohorts or generations, urban-rural populations and so forth, and provide important

indications of the capacity of the nation for economic and social development. ey furnish

material for the comparison of the present educational attainment of the adult population with

the present and anticipated requirements of educated human resources for various types of

economic activities. Such a comparison may serve as a guide both for national policy in terms

of the development of the educational system, and for the planning of the economic develop

ment programmes that it will be feasible to undertake in view of human resource requirements.

3.419. Census information on the economic characteristics of the population focuses on enu

merating the labour force so as to provide benchmark data for current studies of employment

and labour underutilization, in particular unemployment and the potential labour force. It

provides information on the growth, composition and distribution of the labour force for use

in policy formulation and the appraisal of human resource utilization. Economic data from

censuses can also provide some input into statistics on the distribution of income, consump

tion and accumulation of households, and participation in agriculture and non-agricultural

Final Report of the Education for

All Summit of Nine High-Popula-

tion Countries, New Delhi,

12-16 December 1993 (Paris,

UNESCO, 1994).

Principles and Recommendations for Population and Housing Censuses, Revision 3158

activities. Furthermore, the data on the labour force may give an approximate indication of

the number of workers who are responsible for the support of dependants.

3.420. Statistics obtained from diﬀerent sources (for example, labour force surveys, agri

culture surveys, establishment surveys and administrative records) rely on the census for

sampling frames, and the use of common concepts in the diﬀerent sources helps in securing

comparability when multiple sources for changing patterns of economic activity are being

relied upon.

3.421. As interest in the movement of people across national boundaries—in other words,

international migration—has grown steadily among countries, census items and tabulations

relative to international migration have grown in importance. Such tabulations are designed

to assess the impact of migration on receiving countries, to understand patterns of diversity

and develop programmes for the adaptation of migrants to new countries, and to serve as a

source of information on emigration from sending countries.

3.422. e census is also an important source of data on persons with disabilities. Census

data help to monitor the social and living conditions of persons with disabilities in terms of

school attendance, educational attainment, employment, marital status and living arrange

ments. e data also provide a basis for developing policies to meet the needs of persons with

disabilities and for evaluating the eﬀectiveness of these policies.

3.423. e census is also an important source of information on household poverty and

living conditions.

(b) Uses of housing censuses

3.424. e primary uses of information from housing censuses include development of a

basis for planning housing and human settlement programmes and policies, public and pri

vate sector studies of urban and other non-agricultural land use, evaluation of the adequacy

of housing stock and assessment of the need and market for new housing, and studies of the

living conditions of the homeless and those living in temporary or substandard housing.

Information collected on the number of sets, type and characteristics of living quarters and

their occupants is crucial from the point of view of monitoring housing conditions and needs

of the population. Combined with the information collected by regular annual statistical

programmes on housing construction, data from the housing census provide a basis for iden

tifying national, regional and local housing patterns, which are needed for the development

of a rational housing market aimed at stimulating various types of housing construction.

e type and quality of shelter in which people are housed, that is to say, the space, degree

of crowding, facilities, surroundings and available transport, aﬀect their economic activity,

health, social intercourse and general outlook. e supply, characteristics and costs of housing

are therefore subjects for which the housing census is an important source of information.

2. Analysis of the results

3.425. In order to ensure the fullest possible utilization of census results by national and

local governmental authorities, by academic researchers and by others, it is advisable to draw

up a comprehensive and coordinated programme of analytical studies, phased over a period

of several years. is will help allocate eﬀort and resources in such a way as to ensure that

important policy needs are adequately met, undue duplication of research eﬀort is avoided

and priorities are observed as far as possible. In these studies, the data of the current census

should be examined not only by themselves but also as complemented by relevant data from

other sources and from earlier censuses, in order to obtain a broader context, improve the

estimates and establish trends.

159Census operation activities 159

3.426. e analytical studies to be included in such a programme will vary according to the

needs and circumstances of the country. e programme may include descriptive summaries

of results, policy-oriented analyses of census results and detailed analytical studies of one or

more aspects of the demographic and social situation of the country. Some of these studies

may be undertaken by the census organization itself, but others, particularly the more time-

consuming studies, can most eﬀectively be carried out in cooperation with specialists in

diﬀerent subjects having experience in in-depth analytical studies from universities or other

research centres. In any case, it is desirable to invite specialists from other governmental

oﬃces and experts outside government to take part in drawing up this programme of studies,

and it is natural that they would play an important part in the execution of various parts of

the analytical programme.

3.427. One important aspect to be considered in establishing a programme of analysis is

the possible use of census results in achieving the goals and objectives of population, human

settlements or similar policies and strategies at the national and local level, and in applying

available resources eﬀectively towards the improvement of conditions in these ﬁelds. For this

purpose, it will be necessary to analyse population and housing census results within the

framework provided by other available information so as to achieve an integrated approach

to the solutions of population, human settlements and similar problems.

3.428. A permanent census oﬃce should be the central repository of all census results; it

would thus be equipped with the information needed for comparative studies, which will

indicate long-term trends in the phenomena investigated. However, to facilitate the fullest

possible use of census results by others, subsidiary depositories should be established that serve

diﬀerent substantive or geographic groups of users.

3.429. Aside from the studies that are part of the overall census programme, additional

analyses carried out on their own initiative by research organizations, universities or other

experts should be encouraged.

3. Cross-cutting and emerging social issues

3.430. Reﬂecting the concerns and priorities among countries around the world, the

United Nations convened a series of global conferences: on children, education, environment

and climate change, human rights, population, sustainable development, women and human

settlements. Each of these conferences recognized the importance of adequate information

for formulating policy and monitoring progress in the achievement of conference goals, and

called on countries and international organizations to develop and improve the requisite

statistics and indicators. ese recommendations are reﬂected for example in the Vienna

Declaration and Programme of Action of the World Conference on Human Rights;

the

Programme of Action of the International Conference on Population and Development;

the

Copenhagen Declaration on Social Development and the Programme of Action of the World

Summit for Social Development;

the Platform for Action

adopted by the Fourth World

Conference on Women; the Post-2015 Development Agenda Declaration adopted by the

General Assembly; and the Climate Change Declaration. e programmes of action adopted

by these international conferences targeted many interrelated areas of concern, and called for

improved statistics to monitor progress. In deciding which social groups merit monitoring in

regard to measuring the disadvantages suﬀered by particular groups of people, each country

should determine which groups within it need special attention. Some of the common factors

leading to social disadvantage are gender, age, physical or mental impairment, race and creed.

e disadvantaged are not necessarily small in number; they may constitute the majority of

the population.

A/CONF.157/24 (part I), chapter

III.

Report of the International Confer-

ence on Population and Develop-

ment, Cairo, 5-13 September

1994 (United Nations publica-

tion, Sales No. E.95.XIII.18),

chapter I, resolution 1, annex.

Report of the World Sum-

mit for Social Development,

Copenhagen, 6-12 March 1995

( UnitedNations publication,

Sales No. E.96.IV.8), chapter I,

resolution 1, annexes I and II.

Report of the Fourth World Confer-

ence on Women, Beijing, 4-15

September 1995 (United Nations

publication, Sales No. E.96.IV.13),

chapter I, resolution I, annex II.

Note by the Secretary-General

Transmitting the Report of the

Expert Group on the Statistical

Implications of Recent Major

United Nations Conferences

presented to the Working Group

on International Statistical

Programmes and Coordination

at its Eighteenth Session, New

York, 16-19 April 1996 (E/CN.3/

AC.1/1996/R.4), annex, paras.

68-69. .

Principles and Recommendations for Population and Housing Censuses, Revision 3160

3.431. To meet the need for statistics on gender, many activities have been undertaken dur-

ing the last two decades at the national and international levels to improve concepts, deﬁni-

tions and classiﬁcations for collection of statistics related to women and men. In the present

publication, the importance of the population and housing census as a data source has often

been stressed. e population and housing census is also the principal or sometimes the only

comprehensive national data source with respect to meeting the need for statistics on chil

dren, youths, older persons and persons with disabilities in the development of policies and

programmes at the national and international levels. erefore, it is important that countries

identify data requirements concerning various population groups of particular interest when

planning their censuses and ensure that the deﬁnitions and classiﬁcation to be followed in

censuses are appropriate and also consistent with those in use for the entire population.

Use statistical products to measure outcomes and impact measures to spur change

3.432. Furthermore, the census tabulation plan should ensure in advance the inclusion of all

relevant details about special population groups and a range of crossclassiﬁcations for each

group, with a view to analysing its social and economic conditions. Concepts and methods

for the census and the tabulation plan should be reviewed with users concerned with statistics

for each special population group. In the case of some groups, for example persons with dis

abilities, a special set of questions is required to identify members of the group. In the case

of others, standard questions, for example on age, are suﬃcient to identify groups such as

children, youths and older persons. In both cases, most variables needed for cross-tabulations

are already provided for in the international recommendations and many national censuses.

In the census operations, however, attention will often need to be given to improvement of

coverage, quality-of-data issues and avoidance of stereotypic treatment. e present section

deals with gender, a few special population categories such as children and youths, older

persons, and persons with disabilities, so as to assist in the preparing of detailed tabulations

and databases according to international standards.

(a) Statistics on gender

3.433. e global conferences on women have contributed to an increased awareness of the

importance of statistics not only on women but, more broadly, on gender issues. For example,

in developing census plans in a number of countries, eﬀorts have been made to review and

assess the adequacy of statistics for understanding the diversity of both women’s and men’s

lives. It is now recognized that biases in statistics extend, in the case of women, to their

economic roles, and in the case of men, to their roles in the family as husband and father

and their roles in the household. Improvement of statistics and statistical methods related to

gender should be an important priority in all stages of work on the census, in planning, data

collection, analysis and dissemination, and in all other topics.

3.434. In addition to the more general problems of the quality of census data, two other types

of problem that apply particularly to women and stem from gender-based stereotypes and

biases have been noted. Similarly, the notion that only men can be heads of the household

aﬀects the way questions have been designed and asked in censuses. Such stereotypes also

aﬀect the way respondents reply to the questions. A common problem, for example, is clas

sifying women automatically as homemakers without asking whether they perform any work

for pay or proﬁt, even as a part-time or secondary activity.

3.435. Another problem relates to biases in the collection, processing, compilation and pres

entation of data. For example, when census tabulations are prepared for the employed by

occupation, they may be prepared either for males only or for both sexes, but only on the

assumption that information on the occupational pattern of women is not of much use.

Even when tabulations of the employed by occupation are disaggregated by sex, main gender

161Census operation activities 161

diﬀerences in occupations may be missed if the occupation data are presented only at the

two-digit level of the classiﬁcation. Rather, special tabulations showing, for example, the 10

or 20 detailed occupational groups with the highest concentrations of women or men would

be needed to render visible gender-based occupational segregation.

3.436. During the past few decades, considerable eﬀort has been devoted, on the one hand,

to reviewing such bias and its impact on statistics concerning the situation of women and, on

the other hand, to improving the concepts and methods involved in the collection of data in

censuses and surveys. Related improvements in the revised System of National Accounts and

latest recommendations concerning statistics of work, employment and labour underutiliza

tion adopted by the International Conference of Labour Statisticians are also of importance

to the population census. ey are intended to overcome the above-mentioned conceptual

deﬁciencies and to identify and provide measures for all productive activities (that is, forms

of work) performed by women and men, whether paid or unpaid. Similarly, eﬀorts at the

national level have been focused, for example, on eliminating biases in concepts, classiﬁca

tions and deﬁnitions of head of the household.

3.437. Important statistical series and measures on the status of women can be readily

obtained based on the topics in paragraph 4.21 and recommended tabulations for preparation

from censuses. Furthermore, in the case of most topics, the primary unit of classiﬁcation is the

individual, and therefore a vast array of indicators may be obtained by devising appropriate

additional crossclassiﬁcations for the female and male populations separately. For an illustra

tion of census topics and tabulations that are useful for developing comprehensive statistics on

women, see “Statistics and indicators on women and men”,

Handbook for the Development

of National Statistical Data Bases on Women and Development,

Integrating a Gender Perspec-

tive into Statistics

, Methodological Guidelines for the Gender Analysis of National Population

and Housing Census Data.

e household and family status classiﬁcations presented in

paragraph 4.148 are appropriate for analysing the living situation of women and men, with

speciﬁc reference to single mothers and fathers and older women and men living alone.

3.438. It should be emphasized that while all data collected at the individual level can be

presented by sex, this is not always done. Cross-classiﬁcations by sex tend to be suppressed

when cross-tabulations become complex with multiple-variable tables. In order to satisfy

one basic condition for gender statistics, which is that all statistics on individuals should be

presented by sex, sex should be considered the overriding variable in all tables, irrespective of

the medium of storage or dissemination. is disaggregation by gender should be provided

in all publications, databases and computer printouts of census tables on individuals.

3.439. Another important consideration is to broaden the target of dissemination and use of

census data by popularizing the statistics that are published. One approach to achieving this

wide outreach is to present statistics in the form of charts and simpliﬁed tables, with a simple

and clear interpretation of the data. Countries planning to issue an analytical report might

wish to consider using such innovative techniques and formats. e analytical publication

could cover the main census topics or alternatively a few areas that are especially important

to understanding the relative position of women and men in the country.

(b) Statistics on children and youths

3.440. Extensive data on children and youths are available in censuses but may need improve

ments in terms of coverage and quality of information on speciﬁc characteristics, and on their

presentation.

3.441. For statistical purposes, “children” are deﬁned as persons under 15 years of age, and

“youths” are deﬁned as those aged 15-24. However, it is useful to further divide these spe

cial groups by 5-year age groups (or nationally, by groups of speciﬁc school ages) because of

Available from http://unstats

.un.org/unsd/demographic

/products/indwm/indwm2.htm.

United Nations publication,

Sales No. E.89.XVII.9.

United Nations publication,

Sales No. E.13.XVII.9.

UNFPA, 2014.

Principles and Recommendations for Population and Housing Censuses, Revision 3162

the rapid changes in characteristics in this age range, such as in school attendance, marital

status and activity status. Also, because of diﬀerences by sex in the age at marriage, family

or household status and entry into the labour market, data should be classiﬁed not only by

age but also by sex. To this end, the distribution by single years of age and sex is useful. If

single-year age distribution is not feasible for young children under age 5, it would be desir

able to distinguish between those under 1 year of age (infants) and those aged 1-4. For youths

aged 15-19, it would be desirable to distinguish between those 15-17 years of age and those

18-19 years of age, or to have a distinction corresponding to the age below which the country

considers an individual to be a minor.

3.442. For the purpose of developing statistics on children, the principal topics in census

recommendations include (a) sex, (b) age, (c) school attendance (for school-age children) and

(d) relationship to head or other reference member of the household.

3.443. Given the priority on the girl child highlighted by the World Summit for Children

(1990), the International Conference on Population and Development (1994) and the Fourth

World Conference on Women (1995), special attention needs to be given to improving and

disseminating statistics on children. Of particular concern is the situation of the girl child

with respect to school attendance, mortality, early marriage and other issues of importance.

A basic problem with statistics on the girl child is that data on children ever born and children

surviving tend not to be disaggregated by sex at either the questionnaire design or the tabula

tion stage. ese data are used for indirect estimates of child mortality.

3.444. e principal topics of investigation identiﬁed for children apply also to youths, with

the following additions: (a) marital status, (b) literacy, (c) educational attainment, (d) eco

nomic activity status, (e) number of children born alive and (f ) age at marriage.

3.445. Some of the useful statistics and measures can be readily compiled based on the

above-mentioned topics, while any additional indicators can also be obtained based on more

detailed cross-classiﬁcations using the existing recommended census topics or tabulations.

3.446. For older persons also, extensive data are available in population and housing censuses

but may need detailed age-sex classiﬁcation, as described below.

3.4 47. Older persons are deﬁned by the United Nations as all persons aged 60 years and over.

For purposes of classiﬁcation, depending on the national situation, it is useful to tabulate

data by ﬁve-year age groups up to age 100, instead of including them in the single broad age

category 60 and over.

3.448. For the purpose of developing statistics and indicators on older persons, the principal

topics in census recommendations include (a) sex, (b) age, (c) marital status, (d) economic

activity status, (e) income, (f ) household (or family) composition, (g) type of living quarters

and (h) institutional population.

3.449. e statistics needed for studies of older persons are disparate, depending as they do

on national policies and circumstances. Internationally, no illustrative list of indicators is

available to ensure appropriate tabulations from the censuses.

(d) Statistics on persons with disabilities

3.450. e census can provide a valuable source of information on the frequency and dis

tribution of disability in the population, at national, regional and local levels. Experience

shows that although an increasing number of countries ask questions about disability in their

censuses, the presentation of disability data has often been limited to tabulations showing

163Census operation activities 163

the number of speciﬁc severe disabilities present in the population. Unfortunately, cross-

tabulations with other characteristics are not usually made.

3.451. A great deal of work on concepts, classiﬁcations and development of statistics on

persons with disabilities has been undertaken in recent years, particularly through the work

of the Washington Group on Disability Statistics,

and increasing numbers of countries are

including disability as a topic in their censuses. For the second time, recommendations on

including disability questions in a population census are included in these guidelines. A brief

treatment of this topic is given below to highlight issues involved in preparing detailed census

tabulations on persons with disabilities.

3.452. For the purpose of developing statistics on the situation of persons with disabilities

the principal topics in census recommendations that would be necessary for the assessment

of equalization of opportunities include (a) sex, (b) age, (c) place of residence, (d) type of

household, (e) marital status, (f ) educational attainment and school attendance, (g) labour

force status, (h) status of employment, (i) industry and (j) occupation.

3.453. Not only should the tabulation plan for disability data include prevalence rates by sex

and age, but it is also very important that tabulations comparing persons with and without

disabilities on key social and economic characteristics be presented. Tabulations based on the

topics listed above provide information on prevalence of disability and on the situation of

persons with disabilities. In addition, tabulations should be presented in a way that facilitates

comparisons of persons with disabilities and those without.

(e) Ethnocultural characteristics

3.454. Receiving information about the ethnic composition of the population allows deeper

study of the ethnic background of a country’s population, especially with respect to indig

enous population, international migrants and other speciﬁc groups of population (for example

nomads).

3.455. ere are some diﬃculties in collecting this information since some population groups

may name their ethnic identiﬁcation based on its local meaning, and in order to correctly

allocate these persons to their particular ethnic group it is necessary to compile a list of ethnic

groups, sub-ethnic groups and local deﬁnitions of small ethnic population groups. is will

allow for obtaining accurate data about the ethnic composition of population. It would also

be useful if scientists and specialists in the ﬁeld of ethnography, as well as organizations deal

ing with indigenous people, would be involved in creating such a list.

3.456. In order to obtain comprehensive information characterizing ethnic composition of

population, it would be useful to tabulate data by (a) sex, (b) age, (c) place of living, (d) marital

status, (e) birth, (f ) death, (g) education, (h) labour force status, (i) status in employment,

(j) industry, (k) occupation, and (l) type and size of household.

3.457. It is important to obtain comprehensive information on indigenous populations in

order to have statistics on the number as well as the demographic and socioeconomic struc

ture of the given population group. ese data would be valuable information to support the

development of programmes for social support of indigenous peoples.

3.458. Statistics about the ethnic composition of international migrants together with infor

mation about country of birth and citizenship will help to more precisely determine the ﬂows

and volume of international migration.

3.459. Population censuses are also the sources of information about religious identiﬁcation

of the population. It would be useful to obtain this information by (a) sex, (b) age, (c) ethnic

For more information on the

Washington Group on Disability

Statistics, see www.cdc.gov

/nchs/washington_group/index

.htm.

Principles and Recommendations for Population and Housing Censuses, Revision 3164

group, (d) place of living, and (e) place of birth. is information would be useful to study

distribution of religious aﬃliations.

3.460. Information about knowledge of languages is widely used. Countries ﬁnd it useful to

study the oﬃcial language of the country as well as mother tongues or some other languages.

In any case it would be useful to have this information by (a) sex, (b) age, (c) ethnic group,

(d) place of living, and (e) place of birth.

3.461. Information about knowledge of the oﬃcial language of the country would be very

useful for studying the integration of international migrants and may be used, for example,

for development of programmes to learn the language.

3.462. Information about knowledge of the mother tongue of indigenous populations is

very important. is information could allow obtaining statistics of “indigenous” languages

and would be very useful for development programmes to support the development of those

languages.

(f) Statistics on poverty

3.463. e census data can provide a valuable source of information on conditions of life of

households as a proxy measure of poverty to complement quantitative survey data. Census

data provides a quantitative approach to measuring poverty.

3.464. In some cases, countries may compile multiple deprivation indices using census data.

4. Development indicators

3.465. Indicators are required by countries to track the progress of various developmental

goals, and as such eﬀorts must be made by census oﬃces to produce relevant indicators to

meet this need. In the 2010 round of population and housing censuses, most countries pro

duced indicators based on the Millennium Development Goals as was recommended. e

type of indicators necessary to meet international and national reporting requirements need

to be taken into account early in the planning phase of the census.

3.466. It should be emphasized that both global and national reporting and monitoring

require reliable and comparable national data for the compilation of indicators. In this regard,

it is of paramount importance that countries have the statistical capacity to produce, analyse

and disseminate the requisite data for these indicators. e availability of reliable statistics

and the capacity of governments to systematically measure and monitor indicators is a critical

success factor for the achievement of development goals. e lack of statistical capabilities in

some developing countries makes it diﬃcult to obtain good and reliable data. Many countries

do not have a sustainable, coherent programme of household surveys, or administrative data

systems that can be used to produce basic statistics routinely. Where basic statistical systems

are not available, global monitoring may have to rely on national and international estimates

of widely varying quality and reliability. is may lead to misjudgments regarding progress

and may undermine the eﬀectiveness of policy interventions at national and subnational levels.

3.467. Following the adopted of the Millennium Declaration in 2000, the Millennium

Development Goals were set as the world’s time-bound and quantiﬁed targets for addressing

extreme poverty, with a 2015 deadline. It is acknowledged that while the Millennium Devel

opment Goals have made a huge impact in the lives of millions, much remains to be done.

e international community is now engaged in consultative discussions on the post-2015

development agenda in order to address continuing inequalities as well as new challenges

facing people and the planet. Once development goals for the 2015 development agenda

have been adopted they will be incorporated into this section and be made available online.

165Census operation activities 165

XI. Documentation of census experience

3.468. e cumulative experience of past censuses in a country is very useful in the prepara-

tion of a new census. Because of the lapse of time between censuses (generally 10 years) and

the likelihood that experienced staﬀ may leave the census oﬃce, it is essential that there is a

comprehensive record of how the census was planned, organized and conducted.

3.469. e census oﬃce should, therefore, plan for and implement a knowledge management

system to assemble complete records on plans, activities, and decisions taken during the entire

census operation. is would entail documentation and archiving of information related to

plans and their implementation, as well as problems encountered and how they were resolved

at each stage of the census cycle. It is recommended that documentation of census experience

be undertaken at each stage of the census operation and not be left until the end of the census

process. is would include plans, decisions and activities related to preparatory activities, the

methodology of the census, ﬁeldwork or other data collection activity, data processing, cost

and implementation of the census budget, and evaluation of performance of each of these

activities. Examples of items to track or monitor include implementation of activities, time

taken to complete an activity, resources used and cost. All these should be assessed against

set goals so that changes to plans can be recorded, including information on what changed

and why. Tracking and systematically recording the census experience should also take into

account risks encountered and how these risks were managed. For more information see part

two, chapter XIV on “Quality assurance”.

3.470. Use of knowledge management tools and techniques is thus beneﬁcial for preserving

institutional memory in a codiﬁed way so that lessons learned from the past may be used for

better management of future census planning and execution. Records in the system should be

arranged in such a way that information on each aspect of the census operation is found easily.

3.471. Systematic recording of census experience is not an end in itself. It is recommended

that every country prepare and, if possible, publish an administrative and methodological

report, as a census “historical memory”, based on information that has been recorded in

the knowledge management system (see paragraphs 3.325-3.326, “Administrative report”).

Depending on the methodology of the census, the administrative and methodological report

should contain information on the manner in which the census was planned, organized and

conducted, as well as important methodological and other problems encountered at various

stages of the programme. As appropriate, the report should provide specimens of the census

questionnaires and forms, instructions for enumeration, and detailed information on the

cost of the census and on the implementation of the census budget, as well as points to be

considered in future censuses.

3.472. e structure of the report could be similar to the structure of the project plan. It is

important that the report be as comprehensive as possible, covering all stages and aspects of cen

sus planning and operations, including ﬁeldwork, processing, analysis, dissemination and evalu-

ation. It is important to note that while such a report would be based on items and information

in the knowledge management system, it may not necessarily contain detailed descriptions of all

the processes or information, as some may be for internal use only. is report would both assist

the users of the census results in appraising and interpreting the data and facilitate the proper

planning of future data collection programmes, including population and housing censuses.

Principles and Recommendations for Population and Housing Censuses, Revision 3166

XII. Archiving individual records

A. Purpose of archiving individuals records

3.473. e focus of the following elaboration of archiving is on census individual records

irrespective of the format—paper questionnaires or electronic records. e discussion on

the complete process and characteristics of archiving all census documents is presented in

paragraphs 3.468-3.472 on systematic recording and documentation of census experiences.

3.474. Individual census records refer to either census paper questionnaires in the case these

were used for collecting information from the population, or to the digital records on each

enumerated person and household if the data collection did not involve paper questionnaires,

including direct identiﬁers, such as name, address and so forth. In the case of bimodal or

multimodal data collection, that is, a combination of paper and non-paper questionnaires as

in the case of using Internet forms and mail out/mail back paper questionnaires, the resulting

collection of individual records would also be a combination of paper and digital recordings.

3.475. In the case of digital records the accompanying documentation becomes an indispen

sable part of the archiving process. As a number of variables in the digital record are presented

as codes, it is necessary to archive all the codebooks and all the other documentation, such

as the data collection instrument, that are needed for fully unlocking the value of each of

the variables in the record. While this accompanying documentation is also valuable in the

case of archiving paper questionnaires, these are by nature visual, thus requiring only reading

skills and the knowledge of the language initially used for ﬁlling them to grasp the content,

as long as they are in good physical shape.

3.476. e essential purpose of archiving individual census records is to keep them safe for

future use, primarily in the domain of genealogical research and longitudinal social and

anthropological studies, as well as for use by historians and demographers. e release of

archived individual census records is subject to the passage of time as per the census legislation

and usually encompasses many decades, thus ensuring that the use of individual information

would not endanger the conﬁdentiality and the privacy of the respondents.

3.47 7. Consequently, the importance of providing detailed guidance on the process of archiv

ing individual census records in the census legislation cannot be overstated. ese provisions

provide the legal basis for maintaining the archives and procedures related to the release of

archived records. e time lag between the data collection and the release of the archived

records needs to be clearly indicated—it varies from 72 years (United States of America) to 92

years (Canada). In some cases, the original questionnaires are only temporarily stored before

being fully disposed of, as in India, one year before the next census takes place.

B. Procedures for archiving

3.478. Archiving a vast amount of records represents a considerable challenge in all circum-

stances. In the case of individual census records it may be compounded by the sheer number

and format. However, in all cases the national statistical authority needs to develop an insti

tutional strategy for archiving based on three components: organizational infrastructure,

technological infrastructure and resources.

3.479. Organizational infrastructure refers to the arrangements that need to be put in place

within the national statistical oﬃce in such a manner as to ensure the eﬃciency of the archiv

ing and eventual retrieval process. In most cases it is a centralized unit within the oﬃce that is

put in charge of the archiving, maintenance, secure storage and eventual release of individual

records. Once the time lapse mandated by the law for the release of records expires, the actual

167Census operation activities 167

release to the public is usually implemented by dispatching relevant batches to the libraries

covering parts of the country to which the records refer and to a central national library.

3.480. Technological infrastructure refers to the actual technology used for archiving. In con

temporary circumstances, storing huge numbers of paper questionnaires would prove not

to be cost-eﬀective, as it would require a signiﬁcant physically secure structure, regulated

temperature and humidity, and a host of other requirements, including protection from ﬁre

hazards, ﬂoods and extreme weather events. Consequently, in most cases the actual ques

tionnaires are scanned and images of them stored in various electronic storage devices. As an

example, the individual census schedules from the 1940 population and housing census of

the United States are available from a website

in the form of scanned images.

3.481. e technological infrastructure does not refer only to the actual technology used in

the archiving process—it also consists of a series of protocols for archiving and establishing

cross-references that enable successful retrieval of records. In the example of the 1940 United

States census, all the records were archived based on the enumeration district, as the ﬁrst-level

threshold, then county, then district and so forth. erefore, the technology should be built

around a well-developed archiving scheme that enables eﬃcient identiﬁcation and retrieval

of the records.

3.482. In the case of archiving digital records, contemporary technology provides a vast array

of possible solutions—however, it also requires a well thought-over archiving scheme that

needs to ensure eﬃcient storage and retrieval, as well as access to the accompanying metadata

and documentation.

3.483. Resources for archiving need to be taken into account at the early stages of planning for

the census, in the context of the technological and organizational infrastructure. In assessing

the volume of the necessary funds it is necessary to adopt a strategic, long-term approach, as

the archiving, maintaining and releasing would essentially constitute a perpetual activity as

long as censuses are part of the national statistical systems: there would always be a need to

prepare either for the next round of release of records or for archiving the newly acquired one.

C. Archiving individual records and microdata

3.484. Individual census records for archiving purposes as described above diﬀer from census

microdata in a most signiﬁcant manner: they retain the direct identiﬁers—name, address,

enumeration area—as these very identiﬁers represent essential information for genealogical,

anthropological, historical and longitudinal social studies. In the case of microdata, these

identiﬁers would be removed, as well as any others that can directly or indirectly identify the

respondent. Microdata are deﬁned as electronic records pertaining to each unit of observa

tion; in the case of the population and housing censuses, it would be individuals, housing

units and households. is information is stored in variables. Variables can be of diﬀer

ent types (for example, numerical or alphanumerical, discrete or continuous). ey can be

obtained directly from the respondent via a questionnaire or by observation or measurement

(for example, by GPS positioning) or imputed or calculated.

100

3.485. It is expected that the use of anonymized microdata becomes a standard feature of

census data dissemination for the 2020 round of censuses. Consequently, paragraphs 3.376-

3.388 of these Principles and Recommendations present a comprehensive elaboration of prin

ciples and protocols for dissemination of microdata ﬁles.

See http://1940census.archives

.gov/.

100

Olivier Dupriez and Ernie Boyko,

Dissemination of Microdata

Files: Principles, Procedures and

Practices, IHSN Working Paper

No. 005 (2010).

Principles and Recommendations for Population and Housing Censuses, Revision 3168

XIII. Overall evaluation of the census

A. Importance of evaluations

3.486. A population and housing census consists of a complex series of interrelated steps, and

constitutes perhaps the single most extensive, complicated and expensive statistical operation

that a country undertakes. Like any other project, the census needs to be evaluated to ensure

that the eﬀort and investment of resources have been worthwhile.

101

Evaluation of the census

for coverage and also to assess the quality of the data is covered in part three, chapter IX, and

quality assurance for the census in part two, chapter XIV. is section is concerned with the

evaluation processes and procedures of the census operation.

3.487. Evaluation of the census is important for a variety of reasons, among which is to

provide lessons learned from one census to the other. For this reason, evaluation is generally

regarded as the last stage of the census cycle or the ﬁrst step in the next census cycle. Evaluation

assesses the eﬀectiveness of operations, systems and processes and their likely impact on data

quality. In this connection, it is particularly important to assess various aspects of the census

operation, especially when changes have been introduced compared to the previous census.

Assessments provide valuable information on strengths and weaknesses of past operational

procedures, which should be carefully reviewed prior to the development of the next census.

3.488. In addition to evaluation of the conduct and operational elements of the census, it is

valuable to evaluate the use and value of census data and products. Evaluation of the outputs

of the census can be conducted through the conduct of user surveys to gain subjective feed

back or through looking at metrics around product use, for example number of visits to web

products or the number of publications requested or purchased. Evaluation of census products

can be used to measure whether the data and the selected topics are suﬃciently accessible,

timely, relevant, accurate, coherent, trusted and interpretable to meet user requirements. e

outcomes of the evaluation might provide information that can be immediately acted upon

and remedied in the intercensal period, and should certainly feed into the preparations for

the subsequent census.

3.489. In recent years, countries have introduced new methodologies and technologies in

conducting censuses in order to reduce census costs and also to improve the quality and

timeliness of census data. ere is use of new methodologies based on administrative registers

and combinations of sources to produce census information and of new technologies in all

phases of the census. Other changes relate to the use of multimodal enumeration methods as

well as substantial outsourcing of some aspects of census operations.

3.490. Given the current state of aﬀairs, evaluation of processes of census operations becomes

even more warranted in order to assess how well the innovations have worked. Furthermore,

evaluations are necessary so as to provide lessons learned not just for the countries concerned

but also for those that want to adopt similar processes for their future censuses.

B. Planning for the evaluation

3.491. Evaluation of census processes should not be undertaken on an ad hoc basis. e

evaluation programme should be included in the overall census plan and be appropriately

budgeted for. Lack of proper budgeting and planning for activities that come after enumera

tion, such as the post-enumeration survey, has in some cases led to ﬁnancial shortages with

negative consequences for the activities concerned. e success of the programme of evalu

ation depends to a large extent on setting, early enough, clear and unambiguous objectives

101

Handbook on Census Manage-

ment for Population and Housing

Censuses, Revision 1, Studies

in Methods, No. 83/Rev.1

(United Nations publication,

Sales No.E.00.XVII.15 Rev.1).

169Census operation activities 169

to be served by the evaluation. Having clear objectives would help to design the best way to

undertake the evaluation.

3.492. Ascertaining the objectives of the evaluation encompasses other aspects as well. It is

important to establish the scope of the evaluation in terms of intended objectives, keeping

in mind that the wider the scope the more complex the evaluation is likely to be. It should

be noted also that evaluation of census processes and procedures could last several years and

may cover diﬀerent aspects of the census operation, as necessary, thereby resulting in a series

of reports. As for other census activities, there is a cost associated with the evaluation and

the more complex the undertaking or the more processes get evaluated, the higher the cost

is likely to be.

3.493. In addition to the ﬁnancial cost, human resources and skilled staﬀ to undertake

the evaluation should also be planned for. Depending on what aspects of the census opera

tion will be evaluated, the national statistical or census oﬃce should ensure that they have

adequate personnel (in type and quantity) to perform the evaluation. A related issue that

should be taken into account is the extent to which the staﬀ is equipped to undertake the

evaluation. Lack of requisite skilled staﬀ may limit the ability of the country to undertake

some or all of the planned components of the evaluation. An alternative is to hire temporary

staﬀ with the required technical skills to conduct the evaluation or to collaborate with other

agencies such as research institutions.

3.494. As has already been stated, plans for the evaluation of census processes and procedures

should be an integral part of the overall census plan and must be planned for from the start

of census activities. In addition, documentation of the census experience should have the

provision of information for evaluation as one of its objectives. As presented in paragraphs

3.468-3.472 on “Documentation of census experience”, the census organization should have

a knowledge management system to document and archive complete records on plans, activi

ties, and decisions made during the entire census operation, including on problems faced and

how they were resolved. Documented evidence on how the census was undertaken provides

valuable input for the evaluation programme. It should be noted, however, that depending

on what has to be evaluated, some of the information may not be available until the end of

the census operation.

171

Part four

Population and housing census topics

I. Population census topics

A. Factors determining the selection of topics

4.1. In line with the overall approach to revision 3 of Principles and Recommendations

for Population and Housing Censuses, the selection of census topics is based on the outputs

expected to be produced by the census. erefore, the ﬁrst step involves clear identiﬁcation

of user requirements for data; the core and additional topics are then decided on that basis.

For each of the core topics there is a recommended tabulation. It is recommended that

countries collect data on the core topics and also produce the recommended tabulations, as

this would improve the international harmonization and comparability of statistics through

the use of common concepts, deﬁnitions and classiﬁcations. Use of an agreed international

approach would also enhance the capacity of countries to generate statistics for monitoring

the socioeconomic situation of their populations, including for the provision of data for the

internationally agreed development goals.

4.2. e topics to be covered in the census (that is, the subjects regarding which informa

tion is to be sought for each individual or household) should, however, be determined upon

a balanced consideration of:

(a) e needs of the broad range of data users in the country at both the national

and local area level (national priority);

(b) Achievement of the maximum degree of international comparability, both within

regions and on a worldwide basis (international comparability);

of the public to give accurate information on the topics (suitability);

(d) Technical competence of the enumerators in regard to obtaining information on

the topics (suitability);

(e) Total national resources available for conducting the census (resources);

(f ) Availability of relevant information held in alternative data sources (alternative

sources).

4.3. Such a balanced consideration will need to take into account the advantages and

limitations of alternative methods of obtaining data on a given topic within the context of

an integrated national programme for gathering demographic and related socioeconomic

statistics (see paragraphs 1.63-1.68).

4.4. In selecting the population topics, regard should also be given to the usefulness of his

torical continuity, which provides the opportunity for comparison of changes over a period of

time. Census takers should avoid, however, collecting information that is no longer required

by users. Information should not be collected simply because it was traditionally collected

in the past, bearing in mind changes in the socioeconomic circumstances of the country. It

Principles and Recommendations for Population and Housing Censuses, Revision 3172

becomes necessary, therefore, in consultation with a broad range of users of census data, to

review periodically the value of even long-standing topics and to re-evaluate the need for their

continued collection, particularly in the light of new data needs and alternative data sources

that may have become available for investigating topics hitherto covered in the population

census. Each of ﬁve key factors that need to be taken into account in reaching a ﬁnal decision

on census content are brieﬂy reviewed in the following paragraphs.

1. National priority

4.5. Prime importance should be given to the fact that population censuses should be

designed to meet national needs. In deﬁning national data needs for population census data,

the full range of national uses (for example, policy, administration and research) and national

users (for example, national and local government agencies, those in the private sector, and

academic and other researchers) should be considered. e prime consideration is that the

census should provide information on those topics that are of greatest value to the country,

with questions framed so as to elicit data of maximum utility.

4.6. Each country’s decision with regard to the topics to be covered should depend upon

a balanced appraisal of how urgently the data are needed and whether the information could

be equally well or better obtained from other sources. Experience has shown that national

needs will best be served if the census includes topics generally recognized as being of basic

value and deﬁned in accordance with regional and global standards. Global and regional

census recommendations can help in this appraisal by providing information about standard

census topics and related deﬁnitions and concepts based on a wide range of national census

experience. It is recognized however that counties that rely more on administrative records

as their prime data source may be more limited in the precise detail of the information that

can be collected on particular topics.

4.7. Many countries may ﬁnd it necessary to include in the census topics of national or

local interest in addition to the topics included in these recommendations. Labour force or

household survey data may supplement census data to obtain information on topics that can

not be included in the census for whatever reason. It is possible that some countries may omit

from the census certain recommended topics either because there is no need to collect the

data or because there are legal barriers or particular sensitivities in doing so, as for example

may be the case for topics such as fertility, ethnicity and religion.

2. International comparability

4.8. e desirability of achieving regional and worldwide comparability should be another

major consideration in the selection and formulation of topics to be included in the census.

National and international objectives are usually compatible, however, since international

recommendations are based on a broad study of country experience and practice, and the

deﬁnitions and methods contained in international recommendations have successfully met

general national needs in a wide range of circumstances. Furthermore, the analysis of census

data for national purposes will often be facilitated if, through the use of international recom

mendations, it is possible to compare the data with those of other countries on the basis of

consistent concepts, deﬁnitions and classiﬁcations. e post-2015 international development

agenda, which places increasing demand on expanded data collection, is also another deter

mining factor that countries should take into consideration.

4.9. If the particular circumstances within a country require a departure from international

standards, every eﬀort should be made to explain these departures in the census publications

and to indicate how the national presentation can be adapted to the international standards.

173Population and housing census topics 173

3. Suitability

4.10. A prerequisite for the inclusion of topics in the census should be the willingness and

ability of respondents to provide accurate information on them. It is advisable to avoid topics

that could increase the burden on respondents and those that are likely to arouse fear, local

prejudice or superstition or that might be used to deliberately promote political or sectarian

causes as these are likely to have a detrimental eﬀect on response rates and support for the

census. In an interview-based census or where the collector needs to obtain information

through observation, consideration needs to also be given to the level of knowledge and skill

of the interviewer or collector and whether they can be adequately trained to collect this

information accurately. Topics that are too complicated or diﬃcult for the average respond

ent or enumerator to answer quickly should also not be included. e exact phrasing of a

question that will obtain the most reliable responses may depend on national circumstances

and, as described in part three of these recommendations, should be well tested prior to the

census (see paragraphs 3.110-3.114).

4. Resources

4.11. e selection of topics should be carefully considered in relation to the total resources

available for the census. An eﬃcient collection of accurate data for a limited number of topics,

followed by prompt tabulation and publication, is more useful than the collection of data for

an overambitious list of topics that cannot be properly processed and disseminated in a timely,

reliable and cost-eﬀective manner. In balancing the need for data against resources available,

the extent to which questions can be precoded is yet another consideration. Information from

studies on the capacity of users and on the measurement of data utilization may also be an

important factor in determining whether or not it is economically feasible to include certain

topics in the census.

5. Alternative sources

4.12. In the selection of topics to be investigated in a census, consideration should be given

to whether data are available from other sources, taking into account the relative advantages

and limitations of the alternative sources. For example, data may be available from admin

istrative records, or similar data may be collected by household surveys. While household

surveys may not be able to collect the detailed information that can be obtained from cen

suses for small areas or small population groups, there are other advantages associated with

interviewers collecting the data rather than, for example, the information being collected on

a self-enumeration basis or from administrative records—such as, for example, administering

and navigating through probing questions. ose topics for which no alternative sources exist

should be given higher priority while those for which alternative sources are readily available

should be accorded lower priority.

B. List of topics

4.13. e list of topics included in these recommendations for population censuses are

based on the global and regional census experience of the last several decades. e topics

included here are, with some minor revisions, generally the same as those included in the

previous United Nations population census recommendations.

102

However, the concepts and

deﬁnitions for some of the topics relating to economic characteristics have been substantially

revised to reﬂect the more recent recommendations of the International Conference of Labour

Statisticians.

103

102

Principles and Recommen-

dations for Population and

Housing Censuses, Revision 2,

Statistical Papers No. 67/Rev.2

( UnitedNations publication,

Sales No.E.07.XVII.8).

103

For more detail see Nineteenth

International Conference of

Labour Statisticians, Resolution

Concerning Statistics Of Work,

Employment And Labour Underu-

tilization (Geneva, 2013).

Principles and Recommendations for Population and Housing Censuses, Revision 3174

4.14. It should be stressed that no country should attempt to cover all the topics included

in the list of population topics (see table 3). Rather, countries will need to make their selec

tion of topics in light of the considerations discussed in paragraphs 4.1-4.12 above, bearing

in mind any regional recommendations currently pertaining to census topics. In using the

classiﬁcations of diﬀerent topics presented in this part of the Principles and Recommendations

for Population and Housing Censuses, it is necessary to outline that all the one- and two-digit

classiﬁcation levels are recommended, while those at the three-digit level are incorporated for

illustrative and guidance purposes only.

4.15. Evolving census experience over the past several decades globally and in various

regions has demonstrated that a set of topics exist on which there is considerable agreement

in regard both to their importance and to the feasibility of collecting data on them in a

census. Data on those within this set that are found to be excessively costly are probably

best collected through separate surveys of a sample of the population. e exceptions to this

consensus occur, at one extreme, among the countries with the most developed statistical

systems, where adequate data on a number of the topics listed, including some of the core

ones, are available from non-census sources; and, at the other, among the countries in which

data collection opportunities are limited and it is felt that advantage must be taken of the

possibilities oﬀered by the census to investigate topics that, under more ideal circumstances,

might be investigated more suitably by other means.

4.16. Although the set of topics covered in these recommendations is quite comprehensive

in terms of those generally considered suitable for inclusion in a population census, it is also

recognized that some countries may ﬁnd it necessary to include one or more additional top

ics on which information is of particular national or local importance. However, before the

ﬁnal decision is made to include any such additional topics, their suitability should always

be carefully tested.

4.17. To assist countries in using the present publication and in determining their own

priorities, lists of recommended population topics are summarized in paragraph 4.21, with

the core topics shown in boldface. ese core topics correspond to those that were included

as priority topics in the majority of the regional recommendations in previous census decades.

4.18. e topics listed in paragraph 4.21 are grouped into eight categories: geographic

and internal migration characteristics, international migration characteristics, household and

family characteristics, demographic and social characteristics, fertility and mortality, educa

tional characteristics, economic characteristics, and agriculture.

4.19. Within each category, a distinction is made between topics collected directly (those

that appear in the census schedule or questionnaire), and derived topics. Although data for

the derived topics also come from information on the questionnaire, they do not necessar

ily come from replies to a speciﬁc question. Total population, for example, is derived from

a count of the persons entered on the questionnaires as persons present or resident in each

geographic unit. Such derived topics may perhaps be more correctly considered as tabulation

components, but they are listed as topics in order to emphasize the fact that the questionnaire

must in some way yield this information.

4.20. e paragraph numbers in parentheses after each entry in table 3 refer either to the

paragraphs in which the group of topics as a whole is discussed in section IV below or to

the paragraphs in which the deﬁnition and speciﬁcations of individual topics are discussed.

4.21. In the following list of population census topics, core topics are shown in bold and are

represented by  for topics that are collected directly, and by  for those that are derived.

Additional topics are represented by , and additional topics derived from a core topic are

indicated with ∆.

175Population and housing census topics 175

Table 3.

List of population census topics

A. Geographic and internal migration characteristics (paras. 4.50-4.100)

(1) Place of usual residence (paras. 4.52-4.57)



(2) Place where present at time of census (paras. 4.58-4.63)



(3) Place of birth (paras. 4.64-4.71)



(4) Duration of residence (paras. 4.72-4.74)



(5) Place of previous residence (paras. 4.75-4.76)



(6) Place of residence at a speciﬁed date in the past (paras. 4.77-4.81)



(7) Total population (paras. 4.82-4.88)



(8) Locality (paras. 4.89-4.91)



(9) Urban and rural (paras. 4.92-4.100)



B. International migration characteristics (paras. 4.101-4.120)

(1) Country of birth (paras. 4.105-4.109)



(2) Country of citizenship (paras. 4.110 -4.115)



(3) Acquisition of citizenship (paras. 4.116)



(4) Year or period of arrival (paras. 4.117-4.120)



C. Household and family characteristics (paras. 4.121-4.148)

(1) Relationship to the reference person of household (paras. 4.129-4.139)



(2) Household and family composition (paras. 4.140-4.147)



(3) Household and family status (para. 4.148)



D. Demographic and social characteristics (paras. 4.149-4.213)

(1) Sex (para. 4.150)



(2) Age (paras. 4.151-4.162)



(3) Marital status (paras. 4.163-4.171)



(4) Ethnocultural characteristics (paras. 4.172-4.173)



(5) Religion (paras. 4.174-4.178)



(6) Language (paras. 4.179-4.182)



(7) Ethnicity (paras. 4.183-4.187)



(8) Indigenous peoples (paras. 4.188-4.192)



(9) Disability status (paras. 4.193-4.213)



E. Fertility and mortality (paras. 4.214-4.257)

(1) Children ever born alive (paras. 4.228-4.233)



(2) Children living (paras. 4.234-4.236)



(3) Date of birth of last child born alive (paras. 4.237-4.240)



(4) Births in the past 12 months (paras. 4.241-4.243) ∆

(5) Deaths among children born in the past 12 months (paras. 4.244-4.246) ∆

(6) Age, date or duration of ﬁrst marriage (para. 4.247-4.248)



(7) Age of mother at birth of (date or time when) ﬁrst child born alive (para. 4.249)



(8) Household deaths in the past 12 months (paras. 4.250-4.254)



(9) Maternal or paternal orphanhood (paras. 4.255-4.257)



F. Educational characteristics (paras. 4.258-4.288)

(1) Literacy (paras. 4.258-4.264)



(2) School attendance (paras. 4.265-4.271)



(3) Educational attainment (paras. 4.272-4.280)



(4) Field of education and training, and educational qualiﬁcations (paras. 4.281-4.288)



Legend:  Core topic, collected directly

(displayed in bold);  Core topic,

derived;  Additional topic; and ∆ Addi-

tional topic, derived from a core topic.

Principles and Recommendations for Population and Housing Censuses, Revision 3176

G. Economic characteristics (paras. 4.289-4.386)

(3) Labour force status (paras. 4.307-4.338)



(5) Status in employment (paras. 4.339-4.351)



(6) Occupation (paras. 4.352-4.355)



(7) Industry (paras. 4.356-4.359)



(8) Place of work (paras. 4.360-4.365)



(9) Institutional sector of employment (paras. 4.366-4.368)



(10) Working time (paras. 4.369-4.375)



(11) Participation in own-use production of goods (paras. 4.376-4.381)



(12) Income (paras. 4.382-4.386)



H. Agriculture (paras. 4.387-4.396)

(2) Own-account agriculture production (paras. 4.389-4.392)



(3) Characteristics of all agricultural jobs during the last year (paras. 4.393-4.396)



C. Population count

4.22. e main objective of a population census is to provide a reliable basis for an accurate

count of the population of a country at a point in time. An accurate population count is

essential for the eﬃcient planning and delivery of services, distribution of resources, deﬁn

ing of boundaries for electoral representation, policy development and a wide range of other

administrative and statistical purposes.

4.23. A “population count” may be a subset of or the whole of the enumerated popula

tion. A country may have one or more population counts, all derived from the enumerated

population.

4.24. Countries are most interested in the count and distribution of usual residents because

usual residence is generally the best indication of where people will demand and consume

services, and a count of usual residents is therefore most relevant for planning and policy

purposes.

4.25. Some countries will supplement the population count from their census with informa

tion from other sources, for example on usual residents temporarily outside the country at

the time of the census, to produce population estimates. Other countries will rely solely on

the population count from the population census.

4.26. Information about each person can be collected and entered on the census question

naire either where he or she is (or was) present on the day of the census or at his or her usual

residence. Paragraphs 2.46-2.63 describe the place of enumeration basis for the census.

4.27. Population counts may be required on a population present basis, or for the usually

resident population, or some other population base such as a service population. e choice of

population count required will depend on national circumstances; some countries will require

more than one. e information collected about each person by the census will need to enable

the required population counts to be derived. In some cases, for regional comparison purposes,

the population count based on the concept of usual residence might need to be produced.

4.28. e aim of the census is to achieve a full and unduplicated coverage of the population.

In practice, countries face a range of challenges in enumerating the population at the place

they decide (where present on census day or where usually resident), and in producing the

population counts they require. Many of these challenges relate to the diﬃcult-to-enumerate

groups of the population and persons for whom the concept of usual residence is not easily

177Population and housing census topics 177

deﬁned. e latter present an increasing problem as populations become more mobile (nation-

ally and globally) and household and family structures less stable.

4.29. In developing strategies for enumerating the population and collecting information

to support the required population counts, it is important to consider consistency with the

standards for international migration statistics described in paragraphs 4.101-4.104.

1. Population present count

4.30. A population present count is the simplest form of population count from a popula-

tion census. In a questionnaire-based census where no reference is made to usual residence,

people are enumerated at the place where they are found, usually the dwelling where they

spend census night. Foreign residents who are in the country at the time of the census will

be included but usual residents of the country who are absent at that time will be excluded.

4.31. A population present count removes complications associated with the application of

the concept of place of usual residence, and can reduce the incidence of double counting or

missing people if the enumeration is carried out in a single day or reference can be made to the

same census moment for the whole population. Apart from the beneﬁt of simplicity, a popula

tion present count oﬀers a cost advantage because the census does not need to collect additional

information about usual residents not at their usual residence at the time of the census.

4.32. e major disadvantage of a population present count is that it does not enable a full

count of usual residents to be derived, and may not provide a true geographic distribution of

usual residents for eﬀective planning and policy purposes.

4.33. A population present count may be a good proxy for a count and distribution of usual

residents, particularly if nearly all the population will be at their usual residence at the time of

the census, or if the characteristics of those persons present are very similar to the character

istics of usual residents. However, in many countries signiﬁcant numbers of people will not

be at their usual residence at the time of the census, and the characteristics of absent usual

residents will be diﬀerent from non-residents present, so that a population present count is

not always a good proxy for a count of usual residents. Large seasonal movements of people

due to weather changes, employment, holidays and other factors can add to this problem.

e ability to produce accurate information on families and households is also reduced to the

extent that persons are not enumerated with their families or households.

4.34. To produce a population present count, information is required on all persons present

and the address where they are enumerated. It is also very useful to collect information to

identify those persons present who are not at their usual residence and those persons who are

not usual residents of the country.

4.35. Ideally a population present count should include all the persons present at the census

reference moment, regardless of the diﬃculty of their enumeration. For some of these groups

the concept of “at the time of the census” may need to be extended to allow the enumeration

to take place. When, however, the enumeration is extended over a period of time, the risk of

either overcount or undercount may increase. In fact, persons who are at multiple locations

during this extended period may be counted at more than one location, or alternatively they

may not be counted at any location. ose risks increase further when reference is made to a

census period rather than to a census moment.

Principles and Recommendations for Population and Housing Censuses, Revision 3178

2. Usual resident population count

4.36. Countries increasingly prefer a usual resident population count because this count

oﬀers better information for planning and policy purposes on the demand for services, house

holds, families and internal migration.

4.37. A usual resident population count is a count of all usual residents of a country at the

time of the census. Although countries will determine the deﬁnition of a usual resident

according to their own particular circumstances, it is recommended that in deﬁning a usual

resident and the place of usual residence, countries apply the deﬁnition contained in para

graph 2.50. Usual residents may or may not have citizenship of the country, and they may

also include undocumented persons, applicants for asylum or refugees. Usual residents then

may include foreigners who reside (legally or illegally), or intend to reside, in the country

continuously for either most of the last 12 months or for 12 months or more, depending on

the deﬁnition of place of usual residence that is adopted by the country. Persons who may

consider themselves usual residents of a country because of citizenship or family ties, but

were absent from the country for either most of the last 12 months, or for 12 months or

more, depending on the deﬁnition adopted, should be excluded. Conversely, persons who are

normally resident in the country but who are temporarily absent should be included in the

usually resident population. Countries applying a diﬀerent deﬁnition of a usual resident for

national purposes should produce a usual resident population count using the recommended

12-month deﬁnition for the purposes of international comparability.

4.38. A usual resident count provides a comprehensive count of the population of a country

for long-term planning and policy purposes, and a better distribution of the resident popula

tion within the country for planning and service delivery purposes at subnational geographic

levels.

4.39. To achieve a usual resident count, the population can be enumerated either on a place

where present basis or on a where usually resident basis, as described in paragraphs 2.55-2.63.

4.40. To produce a usual resident population count, information is required on all usual

residents and the address of their usual residence, with suﬃcient detail to generate usual resi

dence at the lowest geographic area level required for tabulation. If the census is taken on a

population present basis, then the information collected needs to diﬀerentiate clearly between

persons enumerated at their usual residence, persons usually resident who were elsewhere at

the time of the census, and persons present who are usually resident elsewhere. Information

should also be collected to identify those persons who are not usual residents of the country.

If, however, the census is taken on a usual residence basis, then information about all usual

residents needs to be collected with respect to their usual residence, regardless of whether they

are present at the time of the census or not, to ensure full coverage.

4.41. ere are diﬃculties in obtaining information from those usual residents who are

absent from the country at the time of the census, particularly where no other person is

present at the place of usual residence at the time of the census to provide information about

those people. Estimates or imputations of the number and characteristics of these usual resi

dents not enumerated by the census, and obtained from other sources, will be used by some

countries to supplement the census population count.

4.42. ere can be challenges in applying the concept of a “usual resident” if a person is con

sidered to have more than one residence, sometimes in diﬀerent countries. is is particularly

so for people who may spend parts of the time in communal establishments or institutions,

such as schools or military camps. ere may also be those who do not consider themselves

to have a usual residence at all, such as nomadic peoples or persons sleeping rough. In such

cases place of usual resident can be considered to be the place where they are enumerated.

179Population and housing census topics 179

Countries will need to develop appropriate operational rules for resolving cases where it is

not clear whether a person is a usual resident of the country, or where the usual residence of

the person within the country is not clear.

4.43. ere are population groups for which some uncertainty may arise in deﬁning their

place of usual residence within the country. e recommended conventional treatment of

these cases is as follows:

(a) Persons who work away from home during the week and who return to the fam

ily home at weekends should consider the family home as their place of usual

residence.

(b) Persons of minor age in primary and secondary education who are away from

home during the school term should consider their family home as their place of

usual residence.

versity should consider their term-time address as their place of usual residence

regardless of whether this is an institution (such as a boarding school) or a private

residence.

(d) e institution should be taken as the place of usual residence of all inmates who

at the time of the census have spent, or are likely to spend, six months or more

in the relevant institution. Examples of inmates of institutions include patients

in hospitals or hospices, old persons in nursing homes or convalescent homes,

prisoners and those in juvenile detention centres.

(e) Where a person regularly lives in more than one residence within the country

during the year, the one where he or she spends the majority of the week or year

before the census should be taken as his or her place of usual residence. ese

persons are not considered to be persons with no usual residence.

(f ) For the (national) military, naval and diplomatic personnel and their families

located outside the country the following classiﬁcation rules should be applied:

i. If they are residing abroad for less than 12 months and they are intending

to return to the place of departure, they should be allocated within the

country in accordance with the rules for usual residence. In particular, they

could be allocated to (by decreasing order of priority):

— e family home address within the country, if any;

— e duty station within the country to which they were attached before

leaving.

ii. If they are residing abroad for at least 12 months or if they are not intend

ing to return to the place of departure (although returning to the country

within a 12-month period), they should be attributed to a “virtual region”

(extra-region) of the country of departure.

(g) e place of enumeration should be taken as the place of usual residence of home

less or rooﬂess persons, nomads, vagrants and persons with no concept of usual

residence.

(h) A child who alternates between two households within the country (for instance

after his or her parents have divorced) should consider the household where he or

she spends the majority of the year before the census as his or her place of usual

residence. Where an equal amount of time is spent in both households, the place

of usual residence should be as for the household where the child is staying at the

census reference time.

Principles and Recommendations for Population and Housing Censuses, Revision 3180

3. Other population counts

3.1. Service population count

4.44. A service population count may be required if a population present count or usual resi

dent population count does not accurately represent the demand for, or provision of, services in

a country or part of a country. Service populations are relevant where a signiﬁcant proportion

of the population providing or using services in an area are not usual residents of that area.

Types of service population counts include daytime populations, workplace populations and

visitor populations. In some countries there may also be an interest in foreign service popula

tions, consisting of foreign residents who cross the border regularly to provide or consume

services. is is particularly important in the planning and provision of transport services.

4.45. A service population count may include some or all of the diﬃcult-to-enumerate

groups, depending on the type of service population required.

4.46. To produce a service population count, in addition to an estimate of usual residents,

information is required about where people provide or demand services. For seasonal popula

tions (holiday, resort), information is needed on the destination and timing of seasonal trips.

Some countries will produce service population counts by supplementing the population

present count or usual resident population count with information from other sources, such

as visitor information from hotels and resorts, to produce visitor populations. Alternatively,

additional information may be collected by the census. It should be pointed out that produc

ing a service population count poses diﬃculty due to national circumstances and diﬀerent

practices in the use of data source and method.

3.2. Population subgroups for which counts are required

4.47. Accurate population counts, required for the eﬃcient planning and delivery of ser

vices, distribution of resources, deﬁning of boundaries for electoral representation, policy

development and the design and analysis of household surveys, are required for various popu

lation subgroups within a country. ese subgroups are typically based on geography, age and

sex. ere may also be a need to identify other populations such as the school population,

working population, indigenous population or disadvantaged populations to enable more

informed policy formation and better targeted service provision. A range of characteristics

will be required to identify these populations and population subgroups, depending on the

services being planned, the resources to be distributed and so on. e need for population

counts for particular subgroups will determine the questions asked in the census.

4. Diﬃcult-to-enumerate groups

4.48. e following diﬃcult-to-enumerate groups are relevant to the production of any

population count:

(a) Nomads and persons living in areas to which access is diﬃcult. Making con

tact with these groups to enumerate them can be diﬃcult, particularly as part

of a point-in-time count. Enumeration may need to be done at a diﬀerent time,

over an extended period, or by using alternative methods to enable contact with

these groups. For example, countries might consider asking those who provide

services to these groups to assist with their enumeration. Seasonal movements

may be identiﬁed in advance and this information can be used by collectors to

enable contact. ere needs to be planning and consultation, particularly with

inﬂuential members of these groups, prior to the census to organize for their enu

meration. Communications that publicize the beneﬁts of the census and engaging

appropriate leaders in support of the census may assist coverage. Awareness of

181Population and housing census topics 181

cultural issues relevant to speciﬁc groups should also be considered in developing

enumeration strategies.

(b) Civilian residents temporarily absent from the country. As these persons will be

absent from the country at the time of the census, they will be excluded from a

usual resident population count. To produce a usual resident count countries may

collect information on these people from another family or household member

present at the time of the census, but where a complete family or household is

outside the country at the time of the census, it may not be possible for the census

to collect information about these people. Estimates for usual residents temporar

ily absent from the country based on other sources may be required to produce

reliable estimates of usual residents for planning and policy purposes.

porarily. ese include undocumented persons, or transients on ships in harbour

at the time of the census. ese groups may be in the country at the time of the

census and therefore form part of the population present count. It is important to

include these groups in the population count if their demand for services is to be

considered for planning and policy development purposes. However, these groups

may prefer not be counted, either because they fear ramiﬁcations from being

counted or because they do not identify themselves as part of the population of

the country. Language and communication may present challenges. Countries

need to develop strategies, appropriate for their context, to include these groups

in their enumeration.

(d) Refugees, asylum seekers and internally displaced persons. Refugee popula

tions, asylum seekers and internally displaced persons (in and outside camps)

should be enumerated and their numbers presented separately, allowing calcula

tion of country population excluding such groups, when such a population count

is required for non-demographic purposes.

(e) Military, naval and diplomatic personnel and their families located outside the

country and foreign military, naval and diplomatic personnel and their families

located in the country. Apart from the diﬃculties mentioned in (b) and (c) that

are common to groups who are absent from their own country, enumeration of

these groups is subject to diplomatic protocols. Detailed counts and character

istics of these groups may be considered sensitive on security grounds in some

countries. Counts of these groups may be available from administrative records.

(f ) Civilian foreigners who cross a border daily to work in the country. is group

should be excluded from a usual resident population count. e practice of count

ing people where they spend census night removes much ambiguity and reduces

possible duplication. e diﬃculty then is trying to include them in a service

population if countries want to consider this group in policy development and in

planning service delivery.

(g) Civilian residents who cross a border daily to work in another country. ese

persons are usual residents of the country and should be included in the popula

tion count.

(h) Merchant seafarers and ﬁshers resident in the country but at sea at the time of

the census. is group includes those who have no place of residence other than

their quarters aboard ship. Identifying that the ship will be at sea at the time of

the census may be problematic, so countries will need to develop strategies to

ensure inclusion of this group in the population count. is may include provid

ing this group with census forms before their ship goes to sea or enumerating the

ship before the time of the census.

Principles and Recommendations for Population and Housing Censuses, Revision 3182

(i) Homeless or rooﬂess persons, vagrants and persons with no concept of usual

residence. ese should be included in the population count, and the census

oﬃce should work with local government agencies, charities and other supporting

bodies that provide support for this population group to identify the best method

of collecting census information from these people.

(j) Persons living in buildings with restricted access. Persons living in gated com

munities, condominiums and apartment buildings could be diﬃcult to enumer-

ate, particularly as part of a point-in-time count. Enumeration may need to be

done at a diﬀerent time, over an extended period, or by using alternative methods

to enable contact with these groups.

(k) Stateless persons. ese are individuals who are not considered as nationals by

any State under the operation of its laws. ey are often undocumented and may

not wish to be enumerated. However, every eﬀort should be made to include such

persons in the census. e census oﬃce should work with responsible govern

ment agencies, non-governmental organizations familiar with this population

group and the United Nations High Commissioner for Refugees (UNHCR) to

establish the best method for identifying stateless persons and collecting census

information on them. Country of citizenship is generally essential for the iden

tiﬁcation of this group, though the census oﬃce should consult with relevant

ministries and agencies, including the UNHCR, to determine whether addi

tional information (such as residence history or identity documentation) may be

required to establish the status of a stateless person.

D. Deﬁnitions and speciﬁcations of topics

4.49. e present section contains the recommended deﬁnitions and speciﬁcations of all

topics presented in the order in which they appear in table 3 above. It is important that census

data be accompanied by the deﬁnitions used in carrying out the census. It is also important

that any changes in deﬁnitions that have been made since the previous census are reported

in the metadata and, if possible, accompanied by an assessment of the eﬀect of such changes

on the relevant data, in order to ensure that users will not confuse valid changes over a period

of time with increases or decreases resulting from changed deﬁnitions.

1. Geographic and internal migration characteristics

4.50. It should be noted that “place of usual residence” and “place where present at time

of census” may be considered alternative topics when countries do not have the resources to

investigate both topics for general census purposes. Some countries, however, will want to

investigate both topics for general purposes. e relationship between the two topics and their

further relationship to the topic of “place of enumeration” are set out in part two, chapter IV

(see paragraphs 2.55-2.63).

4.51. It is recommended that countries investigating only “place where present at time of

census” for general purposes should also obtain information on “place of usual residence” for

all persons who do not usually reside in the household where they were enumerated, to be

used in connection with the information on “place of birth”, “duration of residence”, “place

of previous residence” or “place of residence at a speciﬁed date in the past” for the purposes of

determining internal migration status. If, in the compilation of the population of geographic

units, persons are allocated to the place where they were present at the time of the census,

information on the four above-mentioned migration characteristics will be irrelevant for

persons who were only visiting, or transient in, the place at which they were present. Since

183Population and housing census topics 183

such persons must, in any case, be identiﬁed in the questionnaire as non-residents so that

they will not be erroneously classiﬁed as recent in-migrants, information on place of usual

residence should be collected, which will make it possible to include the entire population in

the tabulation of internal migration characteristics.

1.1. Place of usual residence (core topic)

4.52. Information on the number of people usually residing in an area is basic to most

informed decision-making about the area, whether it be a country, an urban agglomeration

or a civil division. e number of residents determines the levels of most services required

in an area.

4.53. e place of usual residence may be the same as, or diﬀerent from, the place where the

enumerated person was present at the time of the census or his or her legal residence. For a

deﬁnition of place of usual residence, see paragraphs 2.48-2.50.

4.54. Although most persons will have no diﬃculty in stating their place of usual residence,

some confusion is bound to arise in a number of situations where persons have more than one

residential address. ese cases might include persons who maintain two or more residences,

students living at school, members of the armed forces living at a military installation but

still maintaining private living quarters away from the installation, and persons who sleep

away from their homes during the working week but return home for several days at the end

of each week (see also paragraph 2.53). In some other circumstances, referring to the person’s

intentions for the future may assist the determination of the place of usual residence.

4.55. Problems may also arise with persons who have (a) been residing at the place where

they are enumerated for some time, perhaps for more than half of the preceding 12 months,

but do not consider themselves to be residents of that place because they intend to return

to their previous residence at some future time; or (b) left the country temporarily but are

expected to return after some time longer than 12 months from the departure. In such

instances, clearly stated time limits of presence in or absence from a particular place must be

based upon the 12-month limit and used to determine whether or not the person is usually

resident there. e 12-month criterion is necessary for determining whether or not a person

is usually resident in the country (so that there is international comparability for migration

purposes), but less so for place of usual residence within the country for measuring internal

migration, where a six-month rule might be more appropriate as it will refer more closely to

the concept of “most of the time”.

4.56. If each person is to be entered in the questionnaire only at his or her place of usual

residence, the topic need not be investigated separately for each person, because the informa

tion will be available from the location information entered for the questionnaire as a whole.

4.57. Information on the place of usual residence should be collected in enough detail to

enable tabulations to be made for the smallest geographic subdivisions required by the tabula

tion plan and to meet the requirements of the database within the cost limits and operational

procedures required to code to a ﬁne degree of detail.

1.2. Place where present at time of census (core topic)

4.58. In cases where the census is taken on the basis of “place where counted”, this topic

may fulﬁl some of the functions of place of usual residence.

4.59. e place where present at time of census is, in theory, the geographic place at which

each person was present on the day of the census, whether or not this was his or her place of

usual residence. In practice, the concept is generally applied to the place where the person was

present at the moment of the census, because many persons may not be physically present at

the place of enumeration during most of the day.

Principles and Recommendations for Population and Housing Censuses, Revision 3184

4.60. As mentioned in part two, chapter IV (see paragraphs 2.57-2.58), the concept is some-

times further extended to apply to the night preceding the day of actual enumeration in cases

where the enumeration extends over a long period of time and persons are not likely to be

able to supply information relating to a single moment in the past. Other departures from the

deﬁnition may be necessary to deal with individual cases, such as persons travelling during

the entire night or day of the census and persons who spent the night at work.

4.61. If each person is to be entered in the questionnaire only at the place where he or she

was present at the time of the census, the topic need not be investigated separately for each

person, because the information will be available from the location information recorded for

the questionnaire as a whole.

4.62. Information on the place where each person was present should be collected in enough

detail to enable tabulation to be made for the smallest geographic subdivisions required by

the tabulation plan and to meet the requirements of the database within the cost limits and

operational procedures required to code to a ﬁne degree of detail.

4.63. For countries that collect information from administrative data sources, the concept

of “present at the time of the census” may not be relevant.

1.3. Place of birth (core topic)

4.64. Information on the place of birth is a major input to development of policies relating

to migration and the related issues of service delivery to migrants. For the purposes of meas

uring internal migration, migrants are deﬁned as those persons who usually are residing in

a civil division of the country at the time of the census, but were previously resident outside

that division. at is, movements within the civil division should not be regarded as being

migratory.

4.65. e place of birth for persons born within the country is the civil division in which

the person was born; for those born in other countries, it is the country of birth. For persons

born in the country (the native-born population), the concept of place of birth usually refers

to the geographic unit where the mother of the individual resided at the time of the person’s

birth. In some countries, however, the place of birth is deﬁned as the geographic unit in which

the birth actually occurred. Either concept can be used depending on the information needs

of the country; but each country should explain the deﬁnitions it uses both in the census

enumerator instructions and in the census reports to aid the interpretation of the data.

4.66. e collection of information distinguishing between the native-born population and

those born elsewhere (foreign-born) is necessary where any enquiry on place of birth is made.

Even countries where the proportion of foreign-born population is insigniﬁcant, and who

may only be interested in information on the place of birth of the native-born population,

must ﬁrst separate the native-born from the foreign-born population. It is therefore recom

mended that place of birth be asked of all persons. In countries that combine the questions

on place of birth and country of birth (where the latter is used to measure international

migration), the guidance on the country of birth (see paragraphs 4.105-4.109) should apply.

4.67. Information on the place of birth of the native population is usually used primarily

for the investigation of internal migration. For countries that have been recently formed from

parts of previously separate entities, however, such information may be of use in assessing

the relative size of the population segments from each of those entities and their distribution

throughout the country.

4.68. Information on whether or not a person is “born in the country” captures the popula

tion according to the boundaries at the time of the census. Using the “born in the country”

185Population and housing census topics 185

concept would account for individuals who may have been aﬀected by changes to a country’s

boundary.

4.69. For the purposes of measuring internal migration, it is usually suﬃcient to collect

information only on the major civil division (state, province or department, for example) in

which the place of birth is located. If desired, more detailed information on the subdivision

of a speciﬁc locality can be collected and used for accurate coding of the major division or

for presenting data for smaller areas.

4.70. However, for more detailed studies of internal migration, data on the place of birth of

the native population even in terms of major civil divisions may not be adequate. For better

understanding of the movements of people since birth it may be necessary to collect informa

tion at the smallest possible geographic level, bearing in mind that:

(a) e boundaries of administrative units such as cities and other civil divisions will

change over time, which may give rise to ambiguity in data reported;

(b) e costs of coding the reported data to these smaller units may be prohibitive,

especially where there are many units and the population is highly mobile.

To overcome the ﬁrst problem, to the extent possible, both national and subnational

boundaries should refer to the boundaries applying at the time of the census. Countries must

address the second problem in light of their own circumstances, bearing in mind the reduced

value of place of birth as a measurement of internal migration in a very mobile population.

4.71. It is recommended that, for the study of internal migration, the data on place of birth

be supplemented by information collected on duration of residence (see paragraphs 4.72-4.74)

and place of previous residence (see paragraphs 4.75-4.76) or on residence at a speciﬁed date

in the past (see paragraphs 4.77 and 4.81).

1.4. Duration of residence (core topic)

4.72. e duration of residence is the interval of time up to the date of the census, expressed

in complete years, during which each person has lived in (a) the locality that is his or her

usual residence at the time of the census; or (b) the major or smaller civil division in which

that locality is situated.

4.73. In collecting information on duration of residence, it should be made clear that the

interest is in length of residence in the major or smaller civil division, or the locality, but not

in the particular housing unit. e concept of duration of residence also relates to the most

recent move to the current place of usual residence.

4.74. Data on the duration of residence have only limited value in themselves because they

do not provide information on the place of origin of in-migrants. erefore, when the topic

is investigated, the place of previous residence should also be investigated, if at all possible,

so that the data can be cross-classiﬁed.

1.5. Place of previous residence (core topic)

4.75. e place of previous usual residence is the major or smaller civil division, or the foreign

country, in which the individual resided immediately prior to migrating into the civil division

of present usual residence.

4.76. Data on the place of previous residence have only limited value in themselves because

they do not provide information on the time of in-migration. erefore, when the topic is

investigated and included in the census, the duration of residence (see paragraphs 4.72-4.74)

should also be included so that the data can be cross-classiﬁed. Alternatively, countries may

Principles and Recommendations for Population and Housing Censuses, Revision 3186

choose to include a question on place of residence as a speciﬁed date in the past (see para-

graphs 4.77-4.81 below).

1.6. Place of residence at a speciﬁed date in the past (core topic)

4.77. e place of usual residence at a speciﬁed date in the past is the major or smaller divi

sion, or the foreign country, in which the individual resided at a speciﬁed date preceding

the census. e reference date chosen should be that most useful for national purposes. In

most cases, this has been deemed to be one year or ﬁve years preceding the census (or both of

these time frames in cases where internal migration is of particular importance to users and

resources are suﬃcient to code the data).

4.78. e former reference date provides information for statistics of both recent internal

and international migration during a single year, while the latter may be more appropriate

for collecting data for longer-term analysis of migration. When selecting the reference date

the ability of individuals to recall with accuracy their usual residence one year or ﬁve years

earlier than the census date should be considered. For countries conducting quinquennial

censuses, the date of ﬁve years earlier can be readily tied in, for most persons, with the time

of the previous census, but it should be noted that a one-year recall is likely to result in more

accurate information than a ﬁve-year recall.

4.79. Some countries, however, may wish to use a diﬀerent time reference than either one

year or ﬁve years preceding the census because these intervals may present recall diﬃculties.

In such circumstances the time reference should be one that can be associated with the occur

rence of an important event that most people will remember.

4.80. For foreign-born persons, the collection of information on year of ﬁrst or last arrival

in the country is recommended (see “International migration characteristics”, paragraphs

4.101-4.120).

4.81. However, no matter what previous date is used, provision must be made for the treat

ment of infants and young children who are resident at the time of the census but were not

yet born at the earlier date. Tabulations of the data should indicate the nature of the treat

ment of this group.

1.7. Total population (core topic)

4.82. For census purposes, the total population of the country consists of all the persons

falling within the scope of the census. In the broadest sense, the total may comprise either all

usual residents of the country or all persons present in the country at the time of the census.

e total of all usual residents is generally referred to as the de jure population and the total

of all persons present as the de facto population.

4.83. In practice, however, countries do not usually fully achieve either type of count,

because one or more groups of the population are included or excluded, depending on

national circumstances. e general term used to describe the total might imply a treatment

opposite to the one given to any of these groups. It is recommended, therefore, that each

country describe in detail the ﬁgure accepted oﬃcially as the total, rather than simply label

it as “de jure” or “de facto”.

4.84. e description should show clearly whether each group listed below was or was not

included in the total. If the group was enumerated and identiﬁed as a separate group, its

magnitude should be given; if it was not enumerated, an estimate of its size and the method of

estimation should be given, if possible. If any group is not represented at all in the population,

this fact should be stated and the magnitude of the group should be shown as “zero”. is may

occur particularly with groups (a), (b), (d) and (n) described below (see also paragraph 4.48).

187Population and housing census topics 187

4.85. e groups to be considered are:

(a) Nomads;

(b) Persons living in areas to which access is diﬃcult;

country;

(d) Merchant seafarers and ﬁshers resident in the country but at sea at the time of the

census (including those who have no place of residence other than their quarters

aboard ship);

(e) Civilian residents temporarily in another country as seasonal workers;

(f ) Civilian residents who cross a border daily to work in another country;

(g) Civilian residents other than those in groups (c), (e) or (f ) who are working in

another country;

(h) Civilian residents other than those in groups (c), (d), (e), ( f ) or (g) who are tem

porarily absent from the country;

(i) Foreign military, naval and diplomatic personnel and their families located in the

country;

(j) Civilian foreigners temporarily in the country as seasonal workers;

(k) Civilian foreigners who cross a frontier daily to work in the country;

(l) Civilian foreigners other than those in groups (i), ( j) or (k) who are working in

the country;

(m) Civilian foreigners other than those in groups (i), ( j), (k) or (l) who are in the

country temporarily;

(n) Refugees in camps;

(o) Transients on ships in harbour at the time of the census.

4.86. In the case of groups (h) and (m), it is recommended that an indication be given of

the criteria used in determining that presence in, or absence from, the country is temporary.

4.87. In those countries where the total population ﬁgure has been adjusted for undercov

erage or overcoverage (or net undercoverage), both the enumerated ﬁgure and the estimated

adjusted population ﬁgure should be shown and described. In such cases, documentation

should be provided for users explaining how the total population ﬁgure from the census has

been adjusted. Ideally, where possible, the detailed tabulations should be consistent with the

adjusted population ﬁgures. However, where this is not possible, if, for example, the costs of

the methodology for undertaking these adjustments are prohibitive, the detailed tabulations

will, of necessity, be based only on the actual enumerated population.

4.88. e population of each geographic unit of the country, like the total population of the

country (see paragraph 4.82), may comprise either all usual residents of the unit (see paragraph

4.53) or all persons present in the unit at the time of the census (see paragraphs 4.58-4.59).

1.8. Locality (core topic)

4.89. For census purposes, a locality should be deﬁned as a distinct population cluster (also

designated as inhabited place, populated centre, settlement and so forth) in which the inhabit

ants live in neighbouring or contiguous sets of living quarters, and that has a name or a locally

recognized status. It thus includes ﬁshing hamlets, mining camps, ranches, farms, market

towns, villages, towns, cities and many other population clusters that meet these criteria.

Any departure from this deﬁnition should be explained in the census report as an aid to the

interpretation of the data.

Principles and Recommendations for Population and Housing Censuses, Revision 3188

4.90. Localities as deﬁned above should not be confused with the smallest civil divisions

of a country. In some cases, the two may coincide. In others, however, even the smallest civil

division may contain two or more localities. On the other hand, some large cities or towns

may contain two or more civil divisions, which should be considered as subdivisions of a

single locality rather than separate localities.

4.91. A large locality (that is to say, a city or a town) is often part of an urban agglomera

tion, which may comprise the city or town proper together with a suburban fringe or heav-

ily populated area lying outside, but adjacent to, its boundaries. e urban agglomeration

is therefore not coterminous with the locality but is an additional geographic unit, which

may include more than one locality. In some cases, a single large urban agglomeration may

comprise several cities or towns and their suburban fringes. e components of such large

agglomerations should be speciﬁed in the census results.

1.9. Urban and rural (core topic)

4.92. Because of national diﬀerences in the characteristics that distinguish urban from

rural areas, the distinction between the urban and the rural population is not yet amenable

to a single deﬁnition that would be applicable to all countries or even, for the most part, to

the countries within a region. Where there are no regional recommendations on the matter,

countries must establish their own deﬁnitions in accordance with their own needs.

4.93. e traditional distinction between urban and rural areas within a country has been

based on the assumption that urban areas, no matter how they are deﬁned, provide a diﬀer

ent way of life and usually a higher standard of living than rural areas. In many developed

countries this distinction has become blurred, and the principal diﬀerence between urban and

rural areas in terms of living standards tends to be the degree of population concentration or

density. On the other hand, the diﬀerences between urban and rural ways of life and standards

of living remain signiﬁcant in developing countries, but even here rapid urbanization in these

countries has created a great need for information related to diﬀerent sizes of urban areas.

4.94. Hence, although the traditional urban-rural dichotomy is still needed, classiﬁcation

by size of locality can usefully supplement the dichotomy, or even replace it where the major

concern is with characteristics related only to density along the continuum from the most

sparsely settled areas to the most densely built-up localities.

4.95. A classiﬁcation of areas as urban or rural should be done at the smallest administra

tive unit of the country, or the smallest census collection unit. e classiﬁcation should be

made, ﬁrst and foremost, on a measure of population density. e distinction between urban

and rural population density depends on the average area of the spatial units being assessed.

Smaller spatial units may need a higher population density threshold and larger spatial units

a lower population density.

4.96. Population density may not, however, be a suﬃcient criterion in many countries, par

ticularly where there are large localities that are still characterized by a truly rural way of life.

Such countries will ﬁnd it necessary to use additional criteria in developing classiﬁcations that

are more distinctive than a simple urban-rural diﬀerentiation. Some of the additional criteria

that may be useful are the percentage of the population engaged in agriculture, the general

availability of electricity or piped water in living quarters and the ease of access to medical

care, schools, recreation facilities and transportation. For certain countries where such facili

ties are available in some areas that are still rural (where agriculture is the predominant source

of employment), it might be necessary to adopt diﬀerent criteria in diﬀerent parts of the

country. Care should be taken, however, to ensure that the deﬁnition used does not become

too complicated for application to the census and for understanding the census results.

189Population and housing census topics 189

4.97. Even in industrialized countries, it may be considered appropriate to distinguish

between agricultural localities, market towns, industrial centres, service centres and so forth,

within size categories of localities.

4.98. Even where size is not used as a criterion, the urban-rural classiﬁcation should be

applied to the locality for national purposes as well as for international comparability. If it is

not possible to use the locality, the smallest administrative unit of the country should be used.

4.99. Some of the information required for classiﬁcation may be provided by the census

results themselves, while other information may be obtained from external sources. e use

of information provided by the census (as, for example, the size class of the locality or the

percentage of the population engaged in agriculture), whether alone or in conjunction with

information from other sources, means that the classiﬁcation will not be available until the

relevant census results have been tabulated. If, however, the census plans call for the inves

tigation of a smaller number of topics in rural areas than in urban areas or for a greater use

of sampling in rural areas, the classiﬁcation must be available before the enumeration takes

place. In these cases, reliance must be placed on external sources of information, even if only

to bring up to date any urban-rural classiﬁcation that was prepared at an earlier date.

4.100. e usefulness of housing census data (for example, the availability of electricity or

piped water) collected simultaneously with, or not too long before, the population census

should be kept in mind. Images obtained by remote sensing may be of use in the demarcation

or boundaries of urban areas when density of habitation is a criterion. For assembling infor

mation from more than one source, the importance of a well-developed system of geocoding

should not be overlooked.

2. International migration characteristics

4.101. Interest in the movement of people across national boundaries, namely, international

migration, has steadily grown among countries concomitant with the increase in international

migration. e decision to collect and disseminate information on international migration in

a census is dependent upon a number of considerations and national circumstances, includ

ing, for example, the national needs for such data. Data on international migrants could

provide information on the diversity of a population and can serve to identify subgroups of

a population. e present section on international migration supplements and expands the

topic “geographic and internal migration characteristics”, which is covered above. Deﬁni

tions of international migration and speciﬁc ways of applying them in population censuses,

consistent with the United Nations Recommendations on Statistics of International Migration,

Revision 1,

104

are presented in this section.

4.102. e revised United Nations Recommendations on Statistics of International Migration

deals with both international migration ﬂows and international migrant stock, and identiﬁes

population censuses as being the main source for collecting data on international migrants

and their characteristics. is section is concerned chieﬂy with the topic of international

migrant stock as derived from population censuses.

4.103. In the Recommendations on Statistics of International Migration (paragraph 185), the

stock of international migrants present in a country is deﬁned as “the set of persons who have

ever changed their country of usual residence, that is to say, persons who have spent at least a

year of their lives in a country other than the one in which they live at the time the data are

gathered”. However, given that this information can be diﬃcult to obtain, it is often approxi

mated by other population groups such as persons born abroad or persons whose country of

citizenship diﬀers from the country they reside in.

104

Statistical Papers, No. 58

( UnitedNations publication,

Sales No. E.98.XVII.14).

Principles and Recommendations for Population and Housing Censuses, Revision 3190

4.104. Consequently, for the study of international migration, census recommendations tend

to focus on two subgroups of the population: the foreign-born population and the foreign

citizens living in the country of enumeration. In order to identify members of those groups,

two items must be recorded in the census: (a) the country of birth, and (b) the country of

citizenship. In addition, it is important to record the year of arrival in the country of enumera

tion so as to establish the length of stay of international migrants residing in the country.

2.1. Country of birth (core topic)

4.105. Country of birth is the country in which the person was born. e concept of county

of birth usually refers to the country where the mother of the individual resided at the time

of the person’s birth. In some countries, however, country of birth is deﬁned as the country in

which the birth actually took place. Either concept can be used depending on the information

needs of the country; each country should explain which deﬁnition it used in the census. It

should be noted that the country of birth of a person is not necessarily the same as his or her

country of citizenship, which is a separate census topic dealt with below. It is recommended

that country of birth be asked of all persons to distinguish the native-born from the foreign-

born population. e collection of this information is necessary even in countries where the

proportion of foreign-born population is small. For the foreign-born population, the col

lection of information on the speciﬁc country of birth is recommended so as to permit the

classiﬁcation of the foreign-born population by country of birth. For respondents who are

born outside the country of enumeration and cannot identify their country of birth, at least

the continent or region where that country is located should be ascertained.

4.106. For purposes of both internal consistency and international comparability, it is recom

mended that information on the country of birth be recorded according to national bounda-

ries existing at the time of the census. Information on the year of arrival in the country (see

paragraph 4.118 below) can be used to identify persons who owe their status of foreign-born to

changes in national boundaries. It is essential that the coding of information on the country of

birth be done in suﬃcient detail to allow for the identiﬁcation of all relevant countries of birth.

4.107. For purposes of coding, it is recommended that countries use the numerical coding

system presented in Standard Country or Area Codes for Statistical Use.

105

e use of standard

codes for classiﬁcation of the foreign-born population according to the country of birth will

enhance the usefulness of such data, including an international exchange of foreign-born

population statistics among countries. If countries decide to combine countries into broad

groups, it is recommended that the standard regional and subregional classiﬁcations identiﬁed

in the above-mentioned publication be adopted.

4.108. Countries with a signiﬁcant number of international migrants may wish to collect

information on the country of birth of parents (both father and mother), in which case

the information should be asked of all respondents following the same guidelines given for

country of birth. e decision to collect and disseminate information on country of birth of

parents in a census is dependent upon a number of considerations and national circumstances,

including for example the suitability and sensitivity of asking such a question that relates to

persons who may not be in the country in which the census is taking place.

4.109. Information on the country of birth of parents can be used, in combination with

information on the country of birth of the enumerated person, to identify native-born chil

dren of the foreign-born population (the so-called “second generation”) and to study the

integration processes and outcomes of migrants and their descendants. Moreover, in countries

that have experienced return migration, information from this topic allows the identiﬁcation

of foreign-born children of native-born parents.

105

United Nations, Standard Country

or Area Codes for Statistical Use,

available from http://unstats

.un.org/unsd/methods/m49

/m49.htm.

191Population and housing census topics 191

2.2. Country of citizenship (core topic)

4.110. Country of citizenship is deﬁned as the country an individual is a citizen of and with

which the individual enjoys a particular legal bond, acquired by birth, naturalization, mar

riage or some other mechanism. A citizen is a legal national of the country of enumeration;

a foreign citizen is a non-national of the country (that is, a citizen of another country or a

stateless person). Because the country of citizenship is not necessarily identical to the country

of birth, both items should be collected in a census.

4.111. Information on the country of citizenship is particularly important for foreign citi

zens. It is important to record country of citizenship as such and not to use another concept to

indicate citizenship, since some of those concepts may also be used to designate ethnic groups.

4.112. It is essential that the coding of information on country of citizenship be done in

suﬃcient detail to allow for the individual identiﬁcation of all countries of citizenship that

are represented among the foreign population in the country. For purposes of coding, it is

recommended that countries use the numerical coding system presented in Standard Country

or Area Codes for Statistical Use. e use of standard codes for classiﬁcation of the foreign

population by country of citizenship will enhance the usefulness of such data and permit

an international exchange of information among countries on their foreign populations. If

countries decide to combine countries of citizenship into broad groups, it is recommended

that the standard regional and subregional classiﬁcations identiﬁed in the above-mentioned

publication be adopted. e category “stateless” should also be listed.

4.113. e reliability of reported citizenship may be doubtful in the case of persons whose

citizenship has recently changed as a result of territorial changes, or among the population of

some newly independent countries where the concept of citizenship may have only recently

become important. Clear guidelines issued by the national statistical authority can help

improve the quality of the data collected. As an aid to the analysis and interpretation of the

results, notes on the likelihood of these and other possible causes of misstatement should

accompany tabulations based on citizenship.

4.114. Enumeration and processing instructions should provide clear guidance on the treat

ment of stateless persons, persons with dual nationality, persons in the process of naturalization

and any other groups with ambiguous citizenship. e treatment of these groups should be

described in the census reports and be included in the metadata for accompanying tabulations.

4.115. In cases where people have more than one citizenship and where this information

is useful for decision-making, details may be collected on whether the person holds one or

multiple citizenship. If this information is to be published, care should be taken to explain

how the possibility of people being included in the table more than once aﬀects the marginal

totals on the table. Usually, however, it may be more practicable for tabulations by citizenship

to refer to one citizenship only. us, persons with multiple citizenships should be allocated

to a single “primary” citizenship, for example by giving precedence to the citizenship of the

“home” country.

2.3. Acquisition of citizenship

4.116. In addition to collecting information on citizenship, for countries where the popula

tion includes a signiﬁcant proportion of naturalized citizens it may be important to collect

information on the method of acquisition of citizenship so as to enable the classiﬁcation of

the population into (a) citizens by birth; (b) citizens by naturalization whether by declaration,

option, marriage or other means; and (c) non-nationals. In such countries it may also be useful

to ask questions on previous citizenship and year of naturalization.

Principles and Recommendations for Population and Housing Censuses, Revision 3192

2.4. Year or period of arrival in the country (core topic)

4.117. Year or period of arrival in the country refers to the calendar year and month of arrival

of a foreign-born person to the country of enumeration. is information enables the calcu

lation of the number of completed years between the time of arrival in the country and the

time of enquiry, usually the census date. Information on the month and year of arrival also

provides the ﬂexibility of classifying foreign-born persons by period of arrival in terms of any

prespeciﬁed period, such as 1975-1979, 1980-1984 and so forth. It is thus recommended that

the period of arrival be shown, in any tabulation in which the variable appears, in terms of

the actual year of arrival.

4.118. It is possible to collect information on either the date of ﬁrst arrival in the country or

the date of the most recent arrival in the country. Each has its own advantages and disadvan

tages. In making the choice of which information to collect, countries should be guided ﬁrst

and foremost by their policy and user needs.

4.119. Information on time since arrival can also be collected by asking how many years

have elapsed since the time of arrival, instead of in what calendar year and month the person

arrived. However, use of such a question is not recommended because it is likely to yield less

accurate information.

4.120. Note that information on the year and month of arrival is focused mainly on persons

born outside the country of enumeration, that is to say, persons who must have arrived in

that country at some time after their birth. However, it should be noted that the phenom

enon of “international return migration” is becoming increasingly common, and countries

that have population groups that maintain links to other countries, migrating to or from

another country at diﬀerent life stages (for example, as students or pensioners), may have an

interest in collecting information on returning migrants: in this case, the question on year

and month of arrival could also be asked of native-born respondents who have ever lived in

another country. In addition, it might also be important to collect information on previous

country of residence for persons who have ever lived abroad.

3. Household and family characteristics

4.121. In considering the topics related to household characteristics, it is important to be

aware of the diﬀerences between the concepts of household and family as used herein.

4.122. A household may be either:

(a) A one-person household, that is to say, a person who makes provision for his or

her own food or other essentials for living without combining with any other

person to form part of a multiperson household; or

(b) A multiperson household, that is to say, a group of two or more persons living

together who make common provision for food or other essentials for living. e

persons in the group may pool their resources and have a common budget; they

may be related or unrelated persons or a combination of persons both related and

unrelated. is arrangement exempliﬁes the “housekeeping” concept.

Some countries use a concept diﬀerent from the housekeeping concept, namely, the

“household dwelling” concept, which regards all persons living in a housing unit as belong

ing to the same household. According to this concept, there is one household per occupied

housing unit. erefore, the number of occupied housing units and the number of households

occupying them are equal and the locations of the housing units and households are identical.

Countries should specify in their census reports whether they used the “housekeeping” or the

“household dwelling” concept of a private household.

193Population and housing census topics 193

4.123. A household may be located in a housing unit (see paragraph 4.427) or in a set of

collective living quarters such as a boarding house, a hotel or a camp, or may comprise the

administrative personnel in an institution.

4.124. e family within the household, a concept of particular interest, is deﬁned as those

members of the household who are related, to a speciﬁed degree, through blood, adoption or

marriage. e degree of relationship used in determining the limits of the family in this sense

is dependent upon the uses to which the data are to be put and so cannot be established for

worldwide use. See paragraph 4.141 for a deﬁnition of the family nucleus.

4.125. Although in practice most households are composed of a single family consisting of a

married couple without children or of one or both parents and their children, it should not be

assumed that this identity always exists; census tabulations should therefore clearly indicate

whether they relate to households or to families within households.

4.126. From the deﬁnitions of “household” and “family”, it is clear that these are diﬀerent

concepts that cannot be used interchangeably in the same census. e diﬀerences between

the household and the family are that:

(a) A household may consist of only one person but a family must contain at least

two members;

(b) e members of a multiperson household need not be related to each other, while

the members of a family must always be related.

4.127. A household can contain more than one family, or one or more families together with

one or more non-related persons, or it can consist entirely of non-related persons. A family

typically will not comprise more than one household. However, the existence of polygamous

families in some countries, as well as shared child custody and support arrangements in

others, means that individual countries should decide how best to derive and report data on

families.

4.128. It is recommended that the household be used as the unit of enumeration (as deﬁned

in paragraphs 2.33-2.38) and that the family be a derived topic only. e place of usual resi

dence is recommended as the basis for assigning persons to households where they normally

reside. Where the de facto approach is used as the method of enumeration (see paragraphs

2.55-2.63), household lists should, where feasible, also include usual residents temporarily

absent. e place of usual residence is where a person usually resides and it may or may not

be the person’s current or legal residence. e latter terms are usually deﬁned in the laws of

most countries and need not correspond to the concept of place of usual residence, which,

as employed in the census, is based on conventional usage. In published reports, countries

should indicate whether or not household information refers to usual residents and also what

the time limits are in respect of being included or excluded as a usual resident. For a more

detailed discussion on the diﬃculty of collecting information on place of usual residence,

see paragraphs 4.52-4.57.

3.1. Relationship to the reference person of household (core topic)

4.129. In identifying the members of a household (as deﬁned in paragraphs 4.122-4.123), it

is useful to identify ﬁrst the household reference person and then the remaining members of

the household according to their relationship to the reference person. Countries may use the

term they deem most appropriate to identify this person (household reference person, head

of household, householder, among others) as long as the person so identiﬁed is used solely to

determine relationships between household members. It is recommended that each country

present, in published reports, the concepts and deﬁnitions that are used.

Principles and Recommendations for Population and Housing Censuses, Revision 3194

4.130. With respect to selecting the household reference person, it is important to specify

criteria for choosing that person in relation to whom household members would be best

distinguished, especially in polygamous, multi-family and other households, such as those

composed only of siblings without a parent and those composed entirely of unrelated persons.

is information should be included in training materials and instructions to enumerators.

4.131. e traditional notion of head of household assumes that most households are family

households (in other words, they consist entirely, except possibly for domestic servants, of

persons related by blood, marriage or adoption) and that one person in such family house

holds has primary authority and responsibility for household aﬀairs and is, in the majority

of cases, its chief economic support. is person is then designated as the head of household.

4.132. Where spouses consider themselves to be equal in household authority and responsi

bility and may share the economic support of the household, the concept of head of household

is no longer considered valid even for family households. In order for the relationship among

members of the household to be determined under these circumstances, it is essential that

either:

(a) e members of the household designate one among them as a reference member

with no implication of headship; or

(b) Provision be made for designation of joint headship where desired.

In any case, it is important that clear instructions be provided in the census as to how

this situation is to be handled.

4.133. Even in the many countries where the traditional concept of head of household is still

relevant, it is important to recognize that the procedures followed in applying the concept

may distort the true picture, particularly with regard to female heads of households. e

most common assumption that can distort the facts is that no woman can be the head of any

household that also contains an adult male. Enumerators and even respondents may simply

take such an assumption for granted.

4.134. is common sex-based stereotype often reﬂects circumstances that may have been

true in the past but are true no longer, insofar as the household and economic roles of women

continue to change. It is therefore important that clear instructions be provided as to who is

to be treated as the reference person of the household so as to avoid the complications of enu

merator or respondent preconceptions on the subject and the bias that such preconceptions

may create. e procedure to follow in identifying a reference person when the members of

the household are unable to do so should be clear and unambiguous and should avoid sex-

based bias. Where alternative deﬁnitions are used, this should be made explicitly in the census

questionnaire and in the tabulated census results.

4.135. e selection of the one reference person in a household to whom all other persons

in the household report, or designate, their relationship requires careful consideration. In

the past the person considered to be the “head of the household” was generally used as the

reference person, but this concept is no longer considered appropriate in many countries. It

has also sometimes been proposed that the person designated as the reference person should

be the oldest person in the household or the one who contributes the most income. However,

given that the primary purpose of the question is to assign family status and to assign indi

viduals into families, both of these approaches have weaknesses. e automatic selection of

the oldest person may be undesirable because in multigenerational households many explicit

kin relationships can be reported where the reference person is selected from the middle gen

eration. Similarly, the selection of the person with the highest income may be a person who

will not solicit the broadest range of explicit kin relationships. Given below is some guidance

on the selection of the reference person, which will yield some explicit kin relationships:

195Population and housing census topics 195

(a) Either the husband or the wife of a married couple living in the household (prefer-

ably from the middle generation in a multigenerational household);

(b) Either partner of a consensual union couple living in the household where there

is no married couple present (where applicable);

(d) Where none of the above conditions apply, any adult member of the household

may be selected.

Note that these categories are neither comprehensive nor mutually exclusive.

4.136. After identiﬁcation of the reference member of the household, each of the remaining

members of the household should be distinguished in relation to that person, as appropriate,

as one of the following:

(a) Spouse;

(b) Partner in consensual union (cohabiting partner), where applicable;

(d) Spouse of child;

(e) Grandchild or great-grandchild;

(f ) Parent (or parent of spouse);

(g) Other relative;

(h) Domestic employee; or

(i) Other person not related to the head or other reference member.

Where this classiﬁcation is considered too detailed for successful collection of the

information, categories (f ) and (g) may be consolidated as “Other relative” and (h) and (i)

can be consolidated as “Other unrelated person”.

4.137. As an aid to the identiﬁcation of family nuclei (as deﬁned in paragraphs. 4.141-4.143)

within the household, it might be helpful if persons were recorded on the census question

naire to the extent possible in the order of nuclear relationship. us, the ﬁrst person entered

after the head or other reference person would be the spouse of that person, followed by

unmarried children and then by married children, their spouses and children. For polyga

mous households, the order of entry could be such that each wife and her unmarried children

appeared in succession.

4.138. For estimating fertility by the own children method (see paragraph 4.217), the natural

mother of each child under 15 years of age should be identiﬁed if she appears in the same

questionnaire as her child. One way of doing this is to provide the line number of the mother

alongside that of the child, if both are living in the same household. e information is not rel

evant for stepchildren, adopted children or foster children under permanent or temporary care.

4.139. In order to meet increased data needs on households and families, countries may wish,

while conducting their population censuses, to collect more detailed information on relation

ships. In households where the relationship structure is complex, including those with foster

children, obtaining accurate information on the relationships between household members

may be diﬃcult. Some countries may supplement information on relationship to the reference

person of the household with information on direct relationships between household mem

bers by, for instance, relating a child to its parents even when neither parent is the reference

person of the household. Enumerators should be encouraged to probe for a clear relationship

(such as child, niece or aunt). e recording of non-speciﬁc responses such as “relative” should

be avoided. It is recommended that speciﬁc guidance be provided on acceptable responses,

Principles and Recommendations for Population and Housing Censuses, Revision 3196

that relationships be speciﬁed completely in the census questionnaire, and that any precoded

categories used should be suﬃciently detailed to produce desired outputs.

3.2. Household and family composition (core topic)

4.140. Household and family composition can be examined from diﬀerent points of view,

but for census purposes it is recommended that the primary aspect considered should be that

of the family nucleus.

4.141. A family nucleus is of one of the following types (each of which must consist of persons

living in the same household):

(a) A married couple without children;

(b) A married couple with one or more unmarried children;

(d) A mother with one or more unmarried children.

106

Couples living in consensual unions may, where appropriate, be regarded as constitut-

ing a family nucleus.

4.142. e concept of family nucleus as deﬁned above limits relationships between children

and adults to direct (ﬁrst-degree) relationships, that is to say, between parents and children.

In some countries, numbers of skip-generation households, that is to say, households consist

ing of grandparent(s) and one or more grandchildren with no parent of those grandchildren

present, are considerable. erefore, countries may include such skip-generation households

in their family nucleus deﬁnition, and the census report should clearly state whether or not

skip-generation households are included in the family nucleus deﬁnition.

4.143. e family nucleus is identiﬁed from the answers to the question on relationship to the

reference member of the household, supplemented where necessary by information on name

and marital status. e identiﬁcation of oﬀspring and their mother and the order in which

persons are entered in the questionnaire may be of additional assistance in this respect. e

identiﬁcation of family nuclei is likely to be more complete in de jure than in de facto enu

merations, because the latter do not take account of temporarily absent household members

who may constitute part of a nucleus.

4.144. For census purposes, a child is any unmarried individual, regardless of age, who

lives with his or her parent(s) and has no children in the same household. Consequently, the

deﬁnition of a child is primarily a function of an individual’s relationship to other household

members, regardless of age. In accordance with this deﬁnition, a household consisting of a

married couple with two never-married children, divorced son, and a married daughter and

her husband would be considered to be composed of two family nuclei, with the divorced

child being regarded as a member of the parents’ family and the married daughter and son-in-

law as a second family. As used here, the term “child” does not imply dependency, but rather is

used to capture household living arrangements of persons who are in a parent-child relation

ship. Countries need to be clear in their metadata how they treat foster and adopted children.

4.145. e family nucleus does not include all family types, such as brothers or sisters living

together without their oﬀspring or parents, or an aunt living with a niece who has no child.

It also excludes the case of a related person living with a family nucleus as deﬁned above, for

example, a widowed parent living with her married son and his family. e family nucleus

approach does not, therefore, provide information on all types of families. Countries may

extend the investigation of families beyond that of the family nucleus, in accordance with

their own interests.

106

In countries where a diﬀerent

deﬁnition of family nucleus is

used, it should be clearly stated

in the census report.

197Population and housing census topics 197

4.146. Households should be classiﬁed by type according to the number of family nuclei

they contain and the relationship, if any, between the family nuclei and the other members of

the household. e relationship should be through blood, adoption or marriage, to whatever

degree is considered pertinent by the country (see paragraph 4.139). Given the complexity of

this item, it is important that information on relationship to the household reference person

be properly processed. e types of household to be distinguished could be:

(a) One-person household;

(d) Nuclear household, deﬁned as a household consisting entirely of a single family

nucleus. It may be classiﬁed into:

i. Married couple family:

a. With child(ren);

b. Without child(ren);

ii. Partner in consensual union (cohabiting partner):

a. With child(ren);

b. Without child(ren);

iii. Father with child(ren);

iv. Mother with child(ren);

107

i. A single family nucleus and other persons related to the nucleus, for exam-

ple, a father with child(ren) and other relative(s) or a married couple with

other relative(s) only;

ii. Two or more family nuclei related to each other without any other persons,

for example, two or more married couples with (or without) child(ren) only;

iii. Two or more family nuclei related to each other plus other persons related

to at least one of the nuclei, for example, two or more married couples with

other relative(s) only;

iv. Two or more persons related to each other, none of whom constitutes a fam

ily nucleus;

(d) Composite household, deﬁned as a household consisting of any of the following:

108

i. A single family nucleus plus other persons, some of whom are related to the

nucleus and some of whom are not, for example, mother with child(ren)

and other relatives and non-relatives;

ii. A single family nucleus plus other persons, none of whom is related to the

nucleus, for example, father with child(ren) and non-relatives;

iii. Two or more family nuclei related to each other plus other persons, some

of whom are related to at least one of the nuclei and some of whom are not

related to any of the nuclei, for example, two or more couples with other

relatives and non-relatives only;

iv. Two or more family nuclei related to each other plus other persons, none

of whom is related to any of the nuclei, for example, two or more married

couples one or more of which has child(ren) and non-relatives;

v. Two or more family nuclei not related to each other, with or without any

other persons;

vi. Two or more persons related to each other but none of whom constitute a

family nucleus, plus other unrelated persons;

vii. Non-related persons only;

(e) Other;

(f ) Unknown or not stated.

107

The subdivisions in this category

should be modiﬁed to suit

national circumstances.

108

The subdivisions in this category

should be modiﬁed to suit

national circumstances.

Principles and Recommendations for Population and Housing Censuses, Revision 3198

4.147. In the census tabulations, all countries should at least distinguish between one-person,

nuclear, extended and composite households. Where feasible, some or all of the subcatego

ries shown above should also be distinguished, although countries may ﬁnd it appropriate

to modify the classiﬁcation according to national circumstances. For example, in countries

where almost all households contain only one family nucleus at most, the distinction between

nuclear, extended and composite households may be applied only to households containing

one nucleus or no nucleus; multinuclear households may then be shown as an additional cat

egory without any further classiﬁcation by type. In countries where multinuclear households

are comparatively common, further breakdowns of extended and composite households,

distinguishing between those with three, four or more family nuclei, may be helpful.

3.3. Household and family status

4.148. For purposes of determining household and family status and identifying how a

person relates to other household or family members, persons may be classiﬁed according to

their position in the household or family nucleus. Classifying persons according to house

hold and family status has uses in social and demographic research and policy formulation.

Census data could be presented according to both household and family status for a variety

of purposes. Although status itself is based on information derived from responses to the item

on relationship to the head or other reference member of the household and other items, the

classiﬁcation of persons by their household and family status is a diﬀerent approach from the

traditional one of classifying household members solely according to their relationship to the

head or reference person. e following household and family status classiﬁcations illustrate

how such an approach may be used.

109

Care should be taken at the planning stages to relate

this item to the classiﬁcation of households by type as recommended in paragraph 4.146.

Persons living in households are classiﬁed by household status as:

1. Person in a household with at least one family nucleus

1.1. Married spouse

1.2. Partner in consensual union (cohabiting partner)

1.3. Lone mother

110

1.4. Lone father

111

1.5. Child living with both parents

1.6. Child living with lone mother

1.7. Child living with lone father

1.8. Not a member of a family nucleus

1.8.1. Living with relatives

1.8.2. Living with non-relatives

2. Person in a household with no family nucleus

2.1. Living alone

2.2. Living with others

112

2.2.1. Living with sibling(s)

2.2.2. Living with other relatives

2.2.3. Living with non-relatives

Persons are classiﬁed by family status as:

113

1. Spouse

1.1. Husband

1.1.1. With child(ren)

1.1.2. Without child

109

To date, only the population and

housing census recommenda-

tions for the Economic Commis-

sion for Europe region contain

household and family status

classiﬁcations.

110

Person living with children,

without spouse.

111

Person living with children,

without spouse.

112

The subdivisions in this category

should be modiﬁed to suit

national circumstances.

113

The subdivisions in this category

should be modiﬁed to suit

national circumstances.

199Population and housing census topics 199

1.2. Wife

1.2.1. With child(ren)

1.2.2. Without child

2. Lone parent

2.1. Male

2.2. Female

3. Child

3.1. With both parents

3.2. With lone parent

3.2.1. With lone father

3.2.2. With lone mother

4. Not member of a family nucleus

4.1. Relative of husband or wife

4.1.1. Parent of husband or wife

4.1.2. Sibling of husband or wife

4.1.3. Other relative of husband or wife

4.2. Non-relative

4. Demographic and social characteristics

4.149. Sex and age are considered to be the most basic of all demographic variables. Of all the

topics included in population censuses, sex and age are more frequently cross-classiﬁed with

other characteristics of the population than are any other topics. Apart from the importance

of the age-sex structure of the population in itself, accurate information on the two topics is

fundamental to the great majority of the census tabulations. A very important use of census

data on the sex and age composition of the population is the evaluation of the data, especially

with respect to coverage. e variables are therefore very crucial, and it is important that this

information be reported in respect of every person for whom census information has been

collected. It is therefore recommended that where this information is incomplete it should

be imputed for census purposes rather than being reported as “not stated”. Possible diﬃcul

ties in securing accurate age data are often not recognized because the topic appears to be a

simple one. e diﬃculties associated with this topic are therefore highlighted in paragraphs

4.151-4.162 below.

4.1. Sex (core topic)

4.150. e sex of every individual should be recorded on the census questionnaire for those

countries that collect their census information in this way. e disaggregation of data by sex

is a fundamental requirement for gender statistics. For many socioeconomic and demographic

characteristics that could be collected through a census, such as education, economic activity,

marital status, migration, disability and living arrangements, there are generally variations by

sex. e successful planning and implementation of gender-sensitive policies and programmes

requires the disaggregation of data by sex to reﬂect problems, issues and questions related

to both men and women in society. Sex, together with age, represents the most basic type

of demographic information collected about individuals in censuses and surveys, as well as

through administrative recording systems, and the cross-classiﬁcation of these data with other

characteristics forms the basis of most analyses of the social and demographic characteristics

of the population, as it provides the context within which all other information is placed.

Principles and Recommendations for Population and Housing Censuses, Revision 3200

4.2. Age (core topic)

4.151. Age is the interval of time between the date of birth and the date of the census,

expressed in completed solar years. Every eﬀort should be made to ascertain the precise and

accurate age of each person, particularly of children and older persons.

4.152. Information on age may be secured either by obtaining the date (year, month and day)

of birth or by asking directly for age at the person’s last birthday.

4.153. e ﬁrst method yields more precise information and should be used whenever cir

cumstances permit. It also allows for the calculation of age at reference dates other than

census day for the purposes, for example, of deriving annual census-based mid- or end-year

population estimates. If neither the exact day nor even the month of birth is known, an indi

cation of the season of the year can be substituted if this information can be easily recorded.

e question on date of birth is appropriate wherever people know their birth date, whether

in accordance with the solar calendar or a lunar calendar, or whether years are numbered or

identiﬁed in traditional folk culture by names within a regular cycle. It is extremely impor

tant, however, that there should be a clear understanding between the enumerator and the

respondent about which calendar system the date of birth is based on. If there is a possibil

ity that some respondents will reply with reference to a calendar system diﬀerent than that

of other respondents, provision must be made in the questionnaire for noting the calendar

system that has been used. It is not advisable for the enumerator to attempt to convert the

date from one system to another. e necessary conversion can be best carried out as part of

the data-editing work.

4.154. Where the information is taken from administrative data sources, date of birth is

usually more accurately recorded.

4.155. e direct question on age is likely to yield less accurate responses for a number of

reasons. Even if all responses are based on the same method of reckoning age, there is the

possibility of a misunderstanding on the part of the respondent as to whether the age wanted

is that at the last birthday, the next birthday or the nearest birthday. In addition, asking a

direct question on age can result in occurrences, with comparative ease, of rounding to the

nearest age ending in zero or ﬁve, providing estimates not identiﬁed as such and deliberate

misstatements. Diﬃculties may arise in the reporting or in the recording of the information

for children under 1 year of age, which may be given erroneously as “1 year of age” rather

than “zero years of age”. ese diﬃculties may be mitigated by collecting information on

the date of birth of all children reported as “1 year of age”, while using only the direct age

question for the remainder of the population. Another possible approach is to obtain age in

completed months for children under 1 year of age. is method, however, can give rise to

another type of recording error, that is to say, the substitution of years for months, so that a

3-month-old child, for example, might be entered in the questionnaire as being 3 years of age.

4.156. Some countries have made improvements in the quality of age data by asking both

questions on age and date of birth.

4.157. An additional complication may occur with the use of the direct question if more

than one method of calculating age is in use in the country. In some countries, certain seg

ments of the population may use an old traditional method whereby persons are considered

to be 1 year of age at the time of birth and everyone advances 1 year in age at the same ﬁxed

date each year. Other segments of the population in the same countries may use the Western

method, in which a person is not regarded as being 1 year of age until 12 months after the

date of birth, and advances 1 year in age every succeeding 12 months. If there is a risk of

diﬀerent methods of age calculation being used by respondents, provision must be made to

201Population and housing census topics 201

ensure that the method used in each case is clearly indicated in the questionnaire and that

the conversion is left to the data-editing stage.

4.158. In spite of its drawbacks, the direct question on age is the only one that should be used

when people cannot provide even a birth year. As regards persons for whom information on

age is unavailable or appears to be unreliable, an estimated age may have to be recorded. is

may occur in isolated cases in societies where knowledge of age is widespread or in general

in cultures where there is little awareness of individual age and no interest in it. In the latter

circumstances, criteria for making estimates should be provided in the instructions for the

enumerators.

4.159. One of the techniques that have been used to aid enumerators consists in providing

them with calendars of historic events of national or local signiﬁcance to be used either in

probing questions or in identifying the earliest event the respondent recalls. Another technique

consists in pre-identifying locally recognized age cohorts in the population and then asking

about membership in the cohorts. Enumerators may also ask if the person in question was born

before or after other persons whose ages have been roughly determined. Furthermore, use can

be made of age norms for weaning, talking, marriage and so forth. Whatever techniques are

used, enumerators should be impressed with the importance of securing age data that are as

accurate as possible within the amount of time that they can devote to the topic.

4.160. In view of the possible diﬃculties in the collection of age data, census tests should be

used, as appropriate, to determine the diﬀerence in results with the use of a question on age

as compared with a question on date of birth, what calendar or method of age reckoning most

people use, and in what parts of the country age will have to be estimated for the majority of

the population and what techniques to use as an aid in estimation. Testing of the calendar

or method of age reckoning that most people use is particularly important where an oﬃcial

change from one calendar or method of reckoning to another calendar or method has taken

place recently enough so that the new calendar or method of reckoning may not yet be in

popular use among some or all of the population.

4.161. Enumerators who are likely to be called upon to estimate age in a substantial number

of cases should be given training in the applicable techniques as part of their general training.

4.162. As noted in paragraph 4.149 it is recommended that where this information is incom

plete it should be derived or imputed for census purposes rather than being reported as “not

stated”.

4.3. Marital status (core topic)

4.163. Despite the changing nature of marriage, marital status remains a useful demographic

variable. e direct relationship between marriage and fertility is still recognized, as is the

indirect relationship with other demographic, social and economic characteristics. Numerous

variations exist in many countries but it is important that marriage be deﬁned in terms of the

laws and customs of individual countries.

4.164. Marital status is the personal status of each individual in relation to the marriage laws

or customs of the country. e categories of marital status to be identiﬁed should at least

include the following:

(a) Single (in other words, never married);

(b) Married;

(d) Widowed and not remarried;

(e) Divorced and not remarried.

Principles and Recommendations for Population and Housing Censuses, Revision 3202

4.165. In some countries, category (b) may require a subcategory of persons who are con-

tractually married but not yet living as man and wife. In all countries, category (c) should

comprise both the legally and the de facto separated, who may be shown as separate subcat

egories if desired.

4.166. In some countries, it will be necessary to take into account customary unions, such

as registered partnerships and consensual unions, which are legal and binding under law.

In countries with legal provision for registered or legal partnership (for opposite-sex couples

or same-sex couples), or where same-sex couples can legally marry, subcategories may either

be included in the category (b) Married or in a legally registered partnership, namely (b)(i)

“Opposite-sex marriage/partnership”, (b)(ii) “Same-sex marriage/partnership”.

4.167. e treatment of persons whose only or latest marriage has been annulled is depend

ent upon the relative size of this group in the country. Where its size is substantial, the group

could constitute an additional category; if its size is insigniﬁcant, however, the individuals

in the group should be classiﬁed according to their marital status before the (annulled) mar

riage took place.

4.168. At times countries have experienced diﬃculties in distinguishing between (a) formal

marriages and de facto unions and (b) persons legally separated and those legally divorced.

If either of these circumstances necessitates a departure from the recommended classiﬁca

tion of marital status, the composition of each category shown in the tabulations should be

clearly stated.

4.169. If complete information on marital status is needed, then this information should be

collected and tabulated for persons of all ages, irrespective of the national minimum legal

age, or the customary age for marriage, because the population may include persons who

were married in another country with a diﬀerent minimum marriage age. In most countries,

there are also likely to be persons who were permitted to marry below the legal minimum

age because of special circumstances. In order to permit international comparisons of data

on marital status, however, any tabulations of marital status not cross-classiﬁed by detailed

age should at least distinguish between persons under 15 years of age and those 15 years of

age and over.

4.170. e collection of additional information related to customs in particular countries

(such as concubinage, polygamous or polyandrous marital status, or inheritance of widows)

may be useful in meeting national needs. For example, at times countries may wish to collect

data on the number of spouses of each married person. Modiﬁcations of the tabulations to

take account of such information should be made within the framework of the basic clas

siﬁcation in order to maintain international comparability as far as possible.

4.171. e concept of marital status and the marital status categories described above should

not be confused with the concept of de facto union status, which describes extralegal unions

(including some consensual unions) of varying degrees of stability common in some coun

tries. It should be recognized also that these marital status categories do not adequately

describe the prevalence of formal legal marriage combined with the relatively stable de facto

union that may exist outside the marriage. Information on these relationships is very useful

in studies of fertility, but it is not possible to provide an international recommendation on

this matter because of the diﬀerent circumstances prevailing among countries. It is suggested,

however, that countries wishing to investigate these relationships should consider the possibil

ity of collecting separate data for each person on de facto unions and on the duration of each

type of union (see paragraphs 4.247-4.248). Information on these relationships can also be

derived from information collected on the relationship to head or reference person or other

persons in the household, in order to distinguish between people who are living in either a

consensual union or marriage, and those who are not.

203Population and housing census topics 203

4.4. Ethnocultural characteristics

4.172. Countries with a culturally diverse population may wish to collect information on the

ethnic identity (or composition) of the population, on mother tongue, on the knowledge and

practice of languages and on religious communities and denominations. ey are all charac

teristics that allow people the ﬂexibility to express their ethnocultural identity in the way that

they choose. Data on such ethnocultural characteristics of the population are of increasing

relevance to countries in the context of migration, integration and minority policies.

4.173. Ethnocultural characteristics generally have a subjective dimension, as there is often

no common understanding as to what characteristic or concept is really being measured in a

particular census. Moreover, diﬀerent countries will adopt diﬀerent concepts. Ethnocultural

characteristics can also be politically sensitive and may apply to very small, yet identiﬁ

able, population subgroups. e free and open declaration of the respondents is therefore of

essential importance. Members of certain minority groups may be particularly vulnerable to

discrimination on the grounds of ethnic group or religion. Special care, therefore, may be

required in census procedures and outputs relating to ethnic group and religion in order to

demonstrate to respondents that appropriate data protection and disclosure control measures

are in place. In some cases, countries may even wish to collect such data on a voluntary basis

if this is permitted by national legislation.

4.5. Religion

4.174. Each country that investigates religion in its census should use the deﬁnition most

appropriate to its needs and should display the deﬁnition that has been used as part of the

metadata in the census publications and dissemination programme.

4.175. For census purposes, religion may be deﬁned as either:

(a) Religious or spiritual belief of preference, regardless of whether or not this belief

is represented by an organized group; or

(b) Aﬃliation with an organized group having speciﬁc religious or spiritual tenets.

4.176. e decision to collect and disseminate information on religion in a national census

is dependent upon a number of considerations and national circumstances, including, for

example, the national needs for such data, and the suitability and sensitivity of asking a reli

gion question in a country’s census. Owing to the sensitive nature of a question on religion,

special care may be required to demonstrate to respondents that appropriate data protection

and disclosure control measures are in place. It is important that the responding public be

informed of the potential uses and needs for this information.

4.177. e amount of detail collected on this topic is dependent upon the requirements

of the country. It may, for example, be suﬃcient to enquire only about the religion of each

person; on the other hand, respondents may be asked to specify, if relevant, the particular

sect to which they adhere within a religion. In countries where a large number of sects or

denominations exist there will be implications for space on any census questionnaire and

implications for data capture, especially in cases where “write-in” responses are required.

In an eﬀort to ensure international comparability as far as possible, it is recommended that

religion or religious aﬃliation should be measured directly by a question that asks “What is

your religion?” rather than use of a ﬁlter question that asks for example “Are you religious?”

and if so “What is your religion?” Response categories should include “No religion/religious

aﬃliation” together with a “Religious but prefer not to disclose” or “Not stated” category, in

eﬀect making responses to such a question voluntary.

4.178. For the beneﬁt of users of the data who may not be familiar with all of the religions

or sects within the country, as well as for purposes of international comparability, the clas

Principles and Recommendations for Population and Housing Censuses, Revision 3204

siﬁcations of the data should show each sect as a subcategory of the religion of which it forms

a part. A brief statement of the tenets of religions or sects that are not likely to be known

beyond the country or region would also be helpful.

4.6. Language

4.179. ere are four types of language data that can be collected in a census, namely:

(a) Mother tongue, deﬁned as the language usually spoken in the individual’s home

in his or her early childhood;

(b) Main language, deﬁned as the language that the person commands best;

by the individual in his or her present home;

(d) Ability to speak one or more designated languages, including the country’s oﬃcial

language(s).

4.180. Each of these types of information serves a very diﬀerent analytical purpose. Each

country should decide which, if any, of these types of information is applicable to its own

needs. International comparability of tabulations is not a major factor in determining the

form of the data to be collected on this topic.

4.181. In compiling data on the usual language or on the mother tongue, it is desirable to

show each language that is numerically important in the country and not merely the domi

nant language.

4.182. Information on language (including any sign language) should be collected for all

persons. In the tabulated results, the criterion for determining language for children not yet

able to speak should be clearly indicated.

4.7. Ethnicity

4.183. e decision to collect and disseminate information on ethnic or national groups

of a population in a census is dependent upon a number of considerations and national

circumstances, including, for example, the national needs for such data, and the suitability

and sensitivity of asking ethnicity questions in a country’s census. Owing to the sensitive

nature of questions on ethnicity, special care may be required to demonstrate to respondents

that appropriate data protection and disclosure control measures are in place. It is important

that the responding public be informed of the potential uses and need for data pertaining to

ethnicity, as this improves public support for the census exercise. Data on ethnicity provide

information on the diversity of a population and can serve to identify subgroups of a popula

tion. Some areas of study that rely on such data include demographic trends, employment

practices and opportunities, income distributions, educational levels, migration patterns and

trends, family composition and structure, social support networks, and health conditions of

a population.

4.184. Broadly deﬁned, ethnicity is based on a shared understanding of history and territo

rial origins (regional and national) of an ethnic group or community, as well as on particular

cultural characteristics such as language or religion. Respondents’ understanding or views

about ethnicity, awareness of their family background, the number of generations they have

spent in a country, and the length of time since immigration are all possible factors aﬀecting

the reporting of ethnicity in a census. Ethnicity is multidimensional and is more a process

than a static concept, and so ethnic classiﬁcation should be treated with movable boundaries.

205Population and housing census topics 205

4.185. Ethnicity can be measured using a variety of concepts, including ethnic ancestry

or origin, ethnic identity, cultural origins, nationality, race, colour, minority status, tribe,

language, religion or various combinations of these concepts. Because of the interpretative

diﬃculties that may occur with measuring ethnicity in a census, it is important that, where

such an investigation is undertaken, the basic criteria used to measure the concept are clearly

explained to respondents and in the dissemination of the resulting data. e method and the

format of the question used to measure ethnicity can inﬂuence the choices that respondents

make regarding their ethnic backgrounds and current ethnic identiﬁcation. e subjective

nature of the term (not to mention increasing intermarriage among various groups in some

countries, for example) requires that information on ethnicity be acquired through self-

declaration of a respondent and also that respondents have the option of indicating multiple

ethnic aﬃliations. Data on ethnicity should not be derived from information on country of

citizenship or country of birth. e classiﬁcation of ethnic groups also requires the inclusion

of the ﬁnest levels of ethnic groups, self-perceived groups, regional and local groups, as well

as groups that are not usually considered to be ethnic groups, such as religious groups and

those based on nationality. Countries collecting data on ethnicity should note that the pre

coding or preclassiﬁcation of ethnic groups at the time of data capture may have a tendency

to lose detailed information on the diversity of a population unless space to record write-in,

free-form responses is provided.

4.186. Respondents should be free to indicate more than one ethnic aﬃliation or a combina

tion of ethnic aﬃliations if they wish so. Countries should explain in the census instructions

and the census documentation how the ethnicity of children from mixed couples is to be

reported (for example, explicit instructions to allow respondents to provide multiple responses

or to allow for responses such as “Biracial”). Also, to guarantee the free self-declaration of

ethnicity, respondents should be allowed to indicate “None” or “Not declared”.

4.187. Because the ethnocultural composition of a country can vary widely from country

to country and due to the diversity in the approach and the various criteria for establishing

ethnicity, it is recognized that there is no single deﬁnition or classiﬁcation that could be rec

ommended that would be applicable to all countries. However, countries should document

the basic criteria and classiﬁcation procedures for ethnicity and inform the data users about

the concepts on which they are based.

4.8. Indigenous peoples

4.188. Facilitating the collection of data on indigenous peoples for national and international

needs can serve to improve socioeconomic and active participation of indigenous peoples in

the development process for many countries. e sensitive nature of questions pertaining to

the indigenous population requires care in assuring the public that the appropriate disclosure

and data protection methods are being enforced. e responding public should be informed

on the potential uses and need for such data to improve public support for the census exercise.

4.189. Dissemination of census data pertaining to indigenous peoples contributes to research

in areas such as the socioeconomic conditions of the indigenous population, trends, causes for

inequities, and the eﬀectiveness of existing policies and programmes. Availability of these data

can also assist indigenous communities in assessing their conditions of living and give them

the information they need to participate and advocate in the development of programmes

and policies aﬀecting their communities, such as those impacting health systems, models of

economic production, environmental management and social organization. In addition, the

development of indicators relevant to the indigenous population and the measurement of such

indicators in the data collection process can be used to monitor the human development of

indigenous populations.

Principles and Recommendations for Population and Housing Censuses, Revision 3206

4.190. Generally, indigenous peoples of a particular country are social groups with an identity

that is distinct from the social and cultural identity of the dominant society in that country.

Questions on indigenous identity should abide by the principle of self-identiﬁcation. It is

important that, where such an investigation is undertaken, multiple criteria are developed to

accurately capture identity and socioeconomic conditions of indigenous peoples. Deﬁning

the indigenous population can be done in many ways, such as through a question on ethnic

origin (that is to say, ancestry) or on indigenous identity. Identifying the indigenous com-

munity also requires recognition of the diversity in this subpopulation, including nomadic,

semi-nomadic and migrating peoples, peoples in transition, displaced persons, indigenous

peoples in urban areas, and particularly vulnerable sects. It is important to point out that

there is no single term among countries to describe the indigenous population. Consequently,

countries tend to use their own national concepts to identify the indigenous population. For

example, in Australia the terms “aboriginal” or “Torres Strait Islander” are used, while in

New Zealand the term “Maori” is used.

4.191. Diﬀering national contexts also imply that enumerating the indigenous population

can be done in multiple ways, for example, by way of speciﬁc questions on the census form,

with specialized questionnaires for the indigenous population, or with follow-up or comple

mentary surveys. In Canada, for example, identiﬁcation of the indigenous population comes

not only from its national census, but also from a post-censal survey. In Australia, in addition

to the national census, there is the National Aboriginal and Torres Strait Islander survey,

while in Argentina there is a complementary survey after the census targeting indigenous

peoples. In addition to a general census, Paraguay also administers a speciﬁc census in the

same year to identify the indigenous population.

4.192. Involvement of the indigenous community in the data development and data collec

tion processes provides the arena for capacity-building and helps to ensure the relevance and

accuracy of the data collection on indigenous peoples. Using local indigenous languages,

employing local indigenous people (as interpreters, for example), and training and building

the capacity of local indigenous people in data collection processes can facilitate the collection

and dissemination of this information. Non-indigenous professionals and technicians should

also be informed of the culture and practices of indigenous peoples.

4.9. Disability characteristics

4.193. A census can provide valuable information on disability in a country. For countries

that do not have regular special population-based disability surveys or disability modules

in ongoing surveys, the census can be the only source of information on the frequency and

distribution of disability and functioning in the population at national, regional and local

levels. Countries that have a registration system providing regular data on persons with the

most severe types of impairments may use the census to complement these data with infor

mation related to selected aspects of the broader concept of disability and functioning based

on the International Classiﬁcation of Functioning, Disability and Health (ICF).

114

Census

data can be utilized for general planning programmes and services (prevention and rehabilita-

tion), monitoring selected aspects of disability trends in the country, evaluation of national

programmes and services concerning the equalization of opportunities, and international

comparison of selected aspects of disability prevalence in countries.

(a) Disability status (core topic)

4.194. Disability status characterizes the population into those with and those without a

disability. Persons with disabilities are deﬁned as those persons who are at greater risk than

the general population for experiencing restrictions in performing speciﬁc tasks or participat

ing in role activities. is group would include persons who experience limitations in basic

activity functioning, such as walking or hearing, even if such limitations were ameliorated

114

Adopted in 2001, the ICF is

the international standard

for describing and measuring

health and disability at both the

individual and population levels.

More information on the ICF

framework is available from

www.who.int/classiﬁcations

/ic f/en/.

207Population and housing census topics 207

by the use of assistive devices, a supportive environment or plentiful resources. Such persons

may not experience limitations in speciﬁcally measured tasks, such as bathing or dressing, or

participation activities, such as working or going to church or shopping, because the necessary

adaptations have been made at the personal or environmental levels. ese persons would still,

however, be considered to be at greater risk of restrictions in activities or participation than

the general population because of the presence of limitations in basic activity functioning,

and because the absence of necessary accommodations would jeopardize their current levels

of participation.

4.195. A comprehensive measure to determine disability would include the following six

domains of functioning in a way that can be reasonably measured using a census and that

would be appropriate for international comparison:

(a) Walking;

(b) Seeing;

(d) Cognition;

(e) Self-care;

(f ) Communication.

4.196. e ﬁrst four domains (a) to (d) are to be considered essential in determining dis

ability status. e additional domains (e) and (f ) comprise a more comprehensive measure

for determining disability.

(b) Use of the census to measure disability at the aggregate level

4.197. A census format oﬀers only limited space and time for questions on any one topic

such as disability. Since ICF oﬀers several dimensions for use to develop a census measure,

it is best to focus on a few of those dimensions, leaving the remaining dimensions for use in

more extensive household surveys. Short sets of disability questions, which can be included

in censuses and extended sets to be recommended for inclusion in population-based surveys,

have been developed and tested by the Washington Group on Disability Statistics.

115

e

aim of the recommended sets is to improve comparability of disability and functioning data

across countries.

4.198. e deﬁnition of disability status (see paragraph 4.194) requires that disability be

deﬁned in terms of limitations in basic activity functioning that would place a person at

greater risk than the general public of restricted performance of or participation in organized

activities (such as educational attendance or work participation). Given the complexity of dis

ability deﬁnition and measurement and, in certain cultures, the sensitivity attached to people

identifying as having a disability, it is recommended that several functional activity domains

be deﬁned whereby people can respond to questions about their diﬃculty in performing

those activities rather than enquiring directly whether or not they have a particular disability.

i. Essential domains

4.199. It is suggested that only those domains that have satisﬁed a set of selection criteria be

eligible for inclusion in a short set of questions recommended for use in censuses. Criteria for

inclusion include cross-population or cross-cultural comparability, suitability for self-reporting

and space on the census form. Other suggested criteria include the importance of the domain

in terms of public health problems. Based on these criteria, the Washington Group on Disabil

ity Statistics has developed a Short Set on Functioning (WG SS-F) questions in the six domains

for the purpose of measuring disability in a census format. e four basic domains are con

115

The Washington Group on Dis-

ability Statistics, a United Nations

City Group that focuses on

proposing international meas-

ures ofdisability, has developed

thesequestions. See www.cdc

.gov/nchs/washington_group

.htm for updates on the question

wording and more information

supporting the collection and

use of data on disability.

Principles and Recommendations for Population and Housing Censuses, Revision 3208

sidered to be essential: walking, seeing, hearing and cognition. In addition, if space permits,

two other domains have been identiﬁed for possible inclusion: self-care and communication.

4.200. Walking fulﬁls the criteria of cross-cultural applicability and space requirements for

comparable data since walking is a good indicator of a central physical function and is a major

cause of limitation in participation.

4.201. While seeing also represents a public health problem, self-reporting of seeing limitation

is more problematic, particularly when individuals use glasses to correct visual impairments.

Similar diﬃculties are associated with asking about hearing activity.

4.202. Assistive devices, such as glasses and hearing aids, provide almost complete accom

modation for a large proportion of those with impaired functioning. It is often argued that

asking about seeing without the use of glasses greatly increases the number of persons with

disabilities and makes the group too heterogeneous, that is, the group would include persons

at very little risk of participation problems along with those at greater risk. As a result, ques

tions on diﬃculty seeing or hearing should be asked with the use of glasses or hearing aids

if they are usually worn.

4.203. Of the four essential domains, cognition is the most diﬃcult to operationalize. Cogni

tion includes many functions such as remembering, concentrating, decision-making, under-

standing spoken and written language, ﬁnding one’s way or following a map, doing math-

ematical calculations, reading and thinking. Deciding on a cross-culturally similar function

that would represent even one aspect of cognition is diﬃcult. However, remembering and

concentrating or making decisions would probably serve the cultural compatibility aspects

the best.

ii. Additional domains

4.204. In additional to the four essential domains, two other have been identiﬁed for possible

inclusion: self-care and communication. e self-care domain is intended to identify persons

who have some problems with taking care of themselves independently. Washing and dressing

represent self-care tasks that occur on a daily basis and are considered to be basic activities.

4.205. e purpose of the communication domain is to identify persons who have some

problems with talking, listening or understanding speech such that it contributes to diﬃculty

in doing their daily activities. Two aspects of communication are considered: understanding

others (receptive communication) and being understood by others (expressive communi

cation). Communicating (understanding and being understood) refers to the exchange of

information or ideas between two people through the use of language.

4.206. Beyond the six domains identiﬁed above, there are further physical functioning

domains that could be included in a set of census questions depending on the space avail

able. e Washington Group Extended Set on Functioning (WG ES-F) includes questions

that address functioning in domains such as upper body (functioning of the arms, hands and

ﬁngers), aﬀect (anxiety and depression), pain and fatigue.

4.207. It is recommended that special attention be paid in designing census questions to

measure disability. e wording and the construct of questions greatly aﬀect the precision in

identifying persons with disabilities. Each domain should be asked through a separate ques

tion.

116

e language used should be clear, unambiguous and simple. Negative terms should

always be avoided. e disability questions should be addressed to each single household

member and general questions on the presence of persons with disabilities in the household

should be avoided. If necessary, a proxy respondent can be used to report for the family

116

When domains are combined,

such as asking a question about

seeing or hearing, respondents

frequently are confused and

think they need to have diﬃ-

culty in both domains in order to

answer yes. In addition, having

the numbers with speciﬁc limita-

tions is useful for both internal

planning and for cross-national

comparisons.

209Population and housing census topics 209

member who is incapacitated. e important thing is to account for each family member

individually rather than ask a blanket question. Scaled response categories can also improve

the reporting of disability. e census questions on disability endorsed by the Washington

Group include four response categories:

(a) No (meaning no diﬃculty at all);

(b) Yes—some diﬃculty;

(d) Cannot do [the activity] at all.

Disability prevalence is determined based on any response that is “a lot of diﬃculty”

or “cannot do at all” for any of the questions.

4.208. e information that results from measuring disability status (see paragraph 4.194)

is expected to:

(a) Represent a large proportion of, but not all, persons with limitation in basic activ

ity functioning in any one country (only the use of a wider set of domains would

potentially cover close to all such persons, but as stated this would not be possible

in a census context);

(b) Represent the most commonly occurring basic activity limitations within any

country;

4.209. e questions identify the population with limitations in basic activities that have the

potential to limit independent participation in society. e intended use of these data would

be to compare levels of participation in employment, education, or family life for those with

disability as measured by the question set versus those without disability to see if persons with

disabilities have achieved social inclusion. In addition, the data could be used to monitor prev

alence trends for persons with limitations in the particular basic activity domains selected.

4.210. Because disability is a complex concept, it is necessary to adopt an explicit deﬁnition

based on the ICF domains used when developing census or survey questions that will be used

to identify disability status. e recommended set of questions for censuses is based on such

an explicit deﬁnition (as described above). It is essential that estimates or tabulations based

on the recommended set be accompanied by information on how disability is deﬁned and

how the questions are asked. is information should be included as part of the metadata

associated with the questions and data set, and it should be included as a footnote to tables

that include these estimates.

(d) Use of census to screen for disability and follow-up with other surveys

4.211. Countries that are planning specialized surveys on disability may want to use the

census to develop a sampling frame for these surveys and include a screening instrument

to identify persons who will be interviewed subsequently. e main purpose of a screening

instrument is to be as inclusive as possible in order to identify the largest group of people who

could be further studied. e screening question should be designed so that false negatives

117

are minimized, while false positives

118

should be less of a concern.

4.212. e same recommendations highlighted in paragraphs 4.207-4.210 should also be

considered when a screening module is designed.

4.213. Before embarking on using the census to develop a frame for a follow-up survey, it

is important that the legal implications of using the census data for this purpose are fully

considered. Respondents should be informed that the data may be used for follow-up studies

117

Persons who have disabilities but

are not identiﬁed in the census

as having disabilities.

118

Persons who are identiﬁed with

disabilities in the census but in

reality do not have disabilities

(as assessed in the largest

instrument used in the follow-up

survey).

Principles and Recommendations for Population and Housing Censuses, Revision 3210

and national authorities responsible for ensuring the privacy rights of the population may

need to be consulted in order to obtain their approval.

5. Fertility and mortality

4.214. e investigation of fertility and mortality in population censuses is particularly

important in countries lacking a timely and reliable system of vital statistics because of the

opportunity the data provide for estimating vital rates that would not otherwise be available.

Even in countries with complete birth and death registration, some of the topics (such as

“children born alive”, “children living”, “age at marriage or union” and “age at ﬁrst birth”) are

equally appropriate because they provide data that are not easily available from registration

data but are necessary for the computation of cohort and period fertility tables. e census

provides an opportunity to collect data for estimating fertility and mortality at national and

subnational levels in a cost-eﬀective manner. e inclusion of these topics in population cen

suses for the purpose of estimating fertility and mortality rates and other related indicators

is both prudent and cost-eﬀective, particularly in countries where civil registration and vital

statistics systems are weak, and costs of conducting large periodic demographic surveys are

high. Nevertheless, it is important to note that census information is a poor substitute for

complete and reliable vital registration data. If countries desire accurate and detailed estimates

of fertility and mortality, they must establish, and need to maintain, civil registration systems

and ensure their universal coverage.

4.215. To obtain information on fertility, information may be collected on “children ever

born”, “date of last child born alive” and “age of mother at birth of ﬁrst child born alive”.

In addition, questions on age, date or duration of marriage or union may improve fertility

estimates based on children ever born (see paragraph 4.247). For the collection of reliable

data, some of the topics may require a series of probing questions that, because they are time-

consuming, are more suitable for use in sample surveys than in censuses.

4.216. e universe for which data should be collected for each of the topics included in

this section consists of women 15 years of age

119

and over regardless of marital status. It is

acknowledged that in some countries certain cultural sensitivities (for example, regarding

the collection of information on childbearing from never-married women) exist towards col

lecting information from all women aged 15 years of age and over without regard to marital

status. In such cases, every eﬀort should be made to collect the information. In countries

that do not use the data for women 50 years of age and over, it may be appropriate to limit

data collection to women under the age of 50, allowing more concentrated eﬀort on data

collection for such women.

4.217. In addition to the topics indicated above that are used to estimate fertility, another

useful topic that allows the estimation of fertility is the “own children” method

120

and birth

history reconstruction.

121

e application of these methods requires the identiﬁcation of the

“natural mother” of each child in the household when the natural mother appears in the same

questionnaire as the child. In cases where it is diﬃcult to ascertain the identity of the natural

mother, one may use as a proxy the relationship to the reference person of the household (see

paragraphs 4.129-4.139) or children living (see paragraphs 4.234-4.236) to establish the

identity of the natural mother. In essence, information on the child’s age and the mother’s

age are used to estimate a series of annual fertility rates for years prior to the census. e reli

ability of the estimates produced depends, among other things, on the proportion of mothers

enumerated in the same questionnaire as their own children, the accuracy of age reporting

for both mothers and their children and the accuracy of available estimates of mortality for

women and children. In the case of subnational estimates, the fertility rates may be aﬀected

119

It may be appropriate in some

countries to reduce the lower

age limit by several years.

120

For methodological details,

see Handbook on the Collection

of Fertility and Mortality

Data, Studies in Methods,

SeriesF, No.92 (United Nations

publication, Sales No. E.03.

XVII.11), chapter V, section B,

available from http://unstats

.un.org/unsd/publication

/SeriesF/SeriesF_92E.pdf;

UnitedNations (1983).

Manual X: Indirect Techniques

for Demographic Estimation,

Population Studies, No.81

(United Nations Publication,

Sales No. E.83.XIII.2), chapterVIII,

section C, available from

www.un.org/esa/population

/publications/Manual_X

/Manual_X.htm; and L-J. Cho,

R.D. Retherford and M.K. Choe,

The Own-Children Method of

Fertility Estimation (Honolulu,

Population Institute, 1987).

121

For methodological details, see

Handbook on the Collection of

Fertility and Mortality Data, Stud-

ies in Methods, Series F, No.92

(United Nations publication,

Sales No. E.03.XVII.11), chapter V,

section C, available from

http://unstats.un.org/unsd

/publication/SeriesF/SeriesF_92E

.pdf; and N.Y. Luther and L-J. Cho,

“Reconstruction of Birth Histo-

ries from Census and Household

Survey Data”, Population Studies

42 (3) (1988), pp. 451-472.

211Population and housing census topics 211

by migration patterns of mothers who leave their children with other family members while

they pursue work elsewhere.

4.218. Mortality topics include infant and child mortality, obtained from data on children

ever born and children living, and adult mortality, obtained from household deaths in the past

12 months and maternal or paternal orphanhood. e extent to which mortality (particularly

infant and child) can be adequately measured from population census data is largely dependent

on the quality of the training of ﬁeld staﬀ to minimize non-response to questions on maternal

and adult mortality and the reporting of erroneous information. Enumerator manuals should

include the measures that are needed to minimize such errors. Accurate responses to the ques

tions described here are often diﬃcult to obtain, thus resulting in faulty data. Nevertheless, it

is often possible to derive usable adjusted estimates from this information.

4.219. As far as possible, eﬀorts should be made to obtain information on fertility, child

mortality (or survival) and marriage directly from the woman or mother involved, because she

is more likely to recall correctly the details of her fertility, the mortality of her oﬀspring and

her marital experiences than any other member of the household. Information on household

deaths, by date, sex and age, in the 12-month period prior to the census should be collected

from the head of the household (or household reference person). Information on maternal

orphanhood and paternal orphanhood should be collected for each person in the household

regardless of age. As with fertility, mortality questions may be limited to a survey sample.

4.220. A number of countries have restricted the collection of data from fertility and mortal

ity questions in the census to a sample of enumeration areas,

122

entailing the introduction of

more vigorous training and permitting the selection of more suitable ﬁeld staﬀ. When those

items are included in the census, certain precautions to ensure accuracy and completeness

should be observed. As mentioned above, every eﬀort should be made to collect all relevant

information directly from the woman concerned. To reduce underreporting of events and to

improve the accuracy of responses to questions on fertility and mortality, enumerators need

to receive speciﬁc training on probing questions that highlight common errors and omissions.

4.221. e limitations of the data collected and of the estimates based on them should be

made clear in the census reports. Furthermore, since some of the estimation procedures are

only suitable for use in certain circumstances, it is important that census data producers

consult specialists or carefully evaluate the methodologies for estimating the indicators for

their appropriateness in a given situation. In general, the data in the basic tabulations resulting

from these questions should not be used for the direct calculation of fertility and mortality

rates. Reliable estimation of fertility and mortality levels using census data requires adjust

ment based on methods of demographic analysis.

123

4.222. As a general guide, only one of the items related to fertility discussed below (“children

ever born”) is recommended for inclusion in all situations. Even in countries with reliable

vital registration of births, census information on this topic can be useful for assessing the

completeness of the registration system and for estimating levels of lifetime fertility for older

cohorts.

4.223. In countries where vital registration of births and deaths is incomplete or unreliable,

it is recommended that a subset of the remaining items should be included as well. Among

these, one item (“date of birth of last child born alive”) is useful for the indirect estimation

of current fertility levels. Two additional items (“children living” and “household deaths in

the past 12 months”) are especially important, as they allow for the indirect estimation of

mortality levels.

4.224. e three remaining items have lower priority: “age, date or duration of ﬁrst marriage/

union”; ”age of mother at birth of ﬁrst child born alive”; and “maternal or paternal orphan

122

For the use of sampling in the

enumeration, see part one,

chapter VI.

123

Manual X: Indirect Techniques

for Demographic Estimation,

Population Studies, No. 81

(United Nations publication,

Sales No. E.83.XIII.2); National

Academy of Sciences Committee

on Population and Demography,

Collecting Data for the Estimation

of Fertility and Mortality,

Report No.6 (Washington, D.C.,

National Academy Press, 1981),

p. 220; Handbook of Population

and Housing Censuses, Part II,

Studies in Methods, No. 54

(United Nations publication,

Sales No. E.91.XVII.9), chapters

III and IV; Step-by-Step Guide

to the Estimation of Child

Mortality, Population Studies,

No. 107 (United Nations

publication, Sales No. E.89.XIII.9);

T.A.Moultrie, R.E. Dorrington,

A.G. Hill, K. Hill, I.M. Timæus

and B. Zaba, eds., Tools for

Demographic Estimation (Paris:

International Union for the

Scientiﬁc Study of Population,

2013), available from

http://demographicestimation

.iussp.org.

Principles and Recommendations for Population and Housing Censuses, Revision 3212

hood”. However, in situations where a country has included one of these items in consecutive

previous censuses, it may be useful to collect comparable information to measure changes

over time and because cohort analysis, particularly of the prevalence of orphanhood, can be

useful in assessing levels of mortality.

4.225. For countries with low fertility and mortality settings, and where the vital registration

is not reliable, further consideration should be given to the item “age of mother at birth of

ﬁrst child born alive”, since it improves the timeliness of estimates of child mortality based

upon children ever born and children surviving.

4.226. In countries with high adolescent birth rates and common child marriages (with large

proportion of women married before age 18), it is recommended that the questions on “age or

date of ﬁrst marriage/union” and “age of mother at birth of ﬁrst child born alive” are included,

since it improves understanding of the spatial distribution of extent of early childbearing and

marriage that surveys cannot provide.

4.227. It is worth emphasizing that all estimates of fertility and mortality derived from

census data are approximate and subject to various sorts of error. erefore, in the absence of

complete and reliable civil registration data, it may be desirable to have more than one type of

census information on each topic (for example, both household deaths in the past 12 months

and maternal or paternal orphanhood for the purpose of estimating adult mortality). Lastly,

it should also be born in mind that while fertility surveys can provide data on current fertility,

they cannot provide the small-area data that the census can. erefore, a fertility question in

the census can still be a priority for many countries.

5.1. Children ever born alive (core topic)

4.228. Information on number of children born alive (lifetime fertility) should include all

children born alive (that is to say, excluding foetal deaths) during the lifetime of the woman

concerned up to the census date. e number recorded should include all live-born children,

whether born in or out of marriage, whether born in the present or a prior marriage, or in a

de facto union, or whether living or dead at the time of the census. In the event of multiple

births (for example twins), each child should be counted as individual birth.

4.229. Data on the total number of live-born children should preferably be collected for all

women 15 years of age

124

and over, regardless of marital status. If, from a cultural standpoint,

it is not acceptable in some countries to attempt to obtain the information for single women,

it should be collected at least for all women 15 years of age and over who are or have been

married or in a union (in other words, all ever-married or ever cohabiting women), a group

that also includes all widowed, divorced and separated women. In either case, the group

of women for whom the data have been collected should be clearly described in the census

report so as to avoid ambiguity in the analysis of the results. In some countries, there can be

substantial misreporting of ages or dates in the census, which distorts fertility and mortality

estimation based on children ever born and children living cross-tabulated by age or years

since ﬁrst birth of the woman.

125

4.230. In order to improve the completeness of coverage and to assist the respondent in recall-

ing her children ever born alive, it is recommended that a sequence of questions be included

in the following order:

(a) “total number of sons ever born alive during the lifetime of the woman”;

(b) “total number of sons living (surviving) at the time of the census”; and

and then:

124

It may be appropriate in some

countries to reduce the lower

age limit by several years.

125

The data on children ever born

and children surviving at the

time of the census become

distorted by errors either in the

reported number of children

ever born and surviving or in

the classiﬁcation of women, in

particular age/duration-of-mar-

riage groups. Such distributions

(biases) result in gross underesti-

mation of fertility and mortality

levels, particularly when data

are disaggregated for small

geographic areas. See Hand-

book on the Collection of Fertility

and Mortality Data, Studies in

Methods. Series F, No.92 (United

Nations publication, Sales No.

E.03.XVII.11), available from

http://unstats.un.org/unsd

/publication/SeriesF/SeriesF_92E

.pdf. For additional methodo-

logical details on the uses of the

data, see T.A. Moultrie, R.E.

Dorrington, A.G. Hill, K. Hill, I.M.

Timæus and B. Zaba, eds., Tools

for Demographic Estimation

(Paris: International Union for the

Scientiﬁc Study of Population,

2013), available from

http://demographicestimation

.iussp.org.

126

As indicated in paragraph 2.146,

couples living in consensual

unions may, where appropriate,

be regarded as married.

213Population and housing census topics 213

(d) “total number of daughters ever born alive during the lifetime of the woman”;

(e) “total number of daughters living (surviving) at the time of the census”; and

(f ) “total number of daughters born alive who have died before the census date”.

e responses to topics (b), (c), (e) and (f ) allow for a checking of the responses to (a)

and (d). Inconsistencies in the ﬁgures, if any, can sometimes be resolved during the interview.

4.231. e number of sons and daughters should comprise all children ever born alive

whether born of the present or a prior marriage or union

126

and should exclude foetal deaths

and adopted children. Also, the number of children, male and female, who are alive at the

time of the census should include those living with the mother in the household and those

living elsewhere, no matter where the latter may reside and regardless of their age and marital

status.

4.232. e collection of data on children ever born speciﬁed by sex not only improves accu

racy of information but also provides data for indirect estimation of sex diﬀerentials in infant

and child mortality, in combination with data on children living (surviving) by sex (see

paragraph 4.234). If the information on “children ever born alive by sex” is collected for

only a sample of women, the data on “children living by sex” should also be obtained for the

same sample.

4.233. Collecting data on the “total number of children ever born alive by sex” is desirable

as it may improve the value of the information by providing a check on their quality, such as

in ascertaining that sex ratios of births follow an expected pattern and do not behave oddly.

5.2. Children living

127

(core topic)

4.234. Data on children living, in conjunction with those on children ever born, are used in

indirect estimation of infant and child mortality in situations where there are no reliable data

from a civil registration.

4.235. It is expected that improved coverage and quality of data on the total number of

children ever born will be achieved if more detailed questions about the current residence of

children ever born are asked, in terms of the following:

(a) “Total number of sons living in the household”;

(b) “Total number of sons living elsewhere”;

(d) “Total number of daughters living in the household”;

(e) “Total number of daughters living elsewhere”;

(f ) “Total number of daughters born alive who have died before the census date”.

ese questions not only give a more complete and accurate reporting of children ever

born alive speciﬁed by sex but also increase the questions’ suitability for subsequent analysis.

4.236. e identiﬁcation of the natural mother of each child under 15 years of age in the same

household, to be used in the “own children” method of estimating fertility (see paragraph

4.217), should be made by asking each woman who reports one or more of her children as

being born alive and living in the household to identify these children in the census ques

tionnaire. e section of the questionnaire on “relationship to the head of the household or

to the reference person in the household” may be used for identifying the natural mother of

each child living in the household.

127

For methodological details on

the uses of the data, together

with data on live-born children,

see the publications mentioned

in footnote 120.

Principles and Recommendations for Population and Housing Censuses, Revision 3214

5.3. Date of birth of last child born alive (core topic)

4.237. Information on date of birth (day, month and year) and sex of the last child born alive

is used for estimating current fertility, and data on the sex of the child can also be used to

evaluate the sex ratio at birth and to detect potential sex-selective birth omissions, misreport

ing or coding errors. is information can be useful as a means of deriving both national and

subnational fertility estimates. In countries lacking adequate data from civil registration, sam

ple surveys have become a major source of information for estimating national fertility levels,

but surveys usually do not permit the derivation of reliable estimates at subnational levels.

4.238. At the data-processing stage, an estimate of the number of live births during the

12 months immediately preceding the census date can be derived from information on “date

of birth of last child born alive”. For estimating current age-speciﬁc fertility rates and other

fertility measures, the data provided by this approach are more accurate than information

that may have been collected in earlier censuses from a question on the number of births to

a woman during the 12 months immediately preceding the census.

128

Information on the

date of birth of the last child born alive provides the number of women who had at least one

live-born child during the 12-month period, not the number of births during the 12-month

period. However, generally only a very small proportion of women will have had more than

one child in a year and hence that omission will not signiﬁcantly aﬀect the fertility estimate

derived from it.

4.239. e information needs to be collected only for women between 15 and 50 years of age

who have reported having at least one live birth during their lifetime. Also, the information

should be collected for all the marital or union status categories of women for whom data

on children ever born by sex (see paragraph 4.228) are collected. If the data on children ever

born are collected for a sample of women, information on date of birth for the last child born

alive should be collected for the same sample.

4.240. A census question on “date of birth of last child born alive” should always be paired

with a simple follow-up question about whether the child is still alive, from which informa

tion on deaths of children born in the last 12 months can be rederived (see paragraph 4.244

below), and which yields data that can be used for studying child mortality (see paragraph

4.250).

5.4. Births in the past 12 months

4.241. Births in the past 12 months refers to the total number of children born alive to the

woman concerned during the 12 months immediately preceding the census. e topic is more

suitable for investigation in a sample survey than in a census.

4.242. Because of errors and omissions commonly encountered in the reporting of live births

within a 12-month retrospective period, this topic by itself cannot generally be relied on to

generate accurate estimates of current fertility. It is recommended that an estimate of the

number of live births during the 12 months immediately preceding the census date be derived

from information on “date of birth of last child born alive” (see paragraph 4.238). For esti

mating current age-speciﬁc fertility rates and other fertility measures, the data provided by

this approach are more accurate than information that may have been collected in earlier cen

suses from a question on the number of births to a woman during the 12 months immediately

preceding the census.

129

Only if a country’s population is characterized by low levels of date

numeracy—that is, there is a strong indication of deﬁcient accuracy of the replies—should

a direct question on number of births in the last 12 months be asked. In all other cases, the

core question on date of last child born alive should be suﬃcient.

128

The approach to calculating

fertility rates from these data

is described in T.A. Moultrie,

“Evaluation of data on recent

fertility from censuses”, in Tools

for Demographic Estimation,

T.A.Moultrie, R.E. Dorrington,

A.G. Hill, K. Hill, I.M. Timæus and

B. Zaba, eds. (Paris, International

Union for the Scientiﬁc Study of

Population, 2013), available from

http://demographicestimation

.iussp.org/content/evaluation-

data-recent-fertility-censuses.

129

Ibid.

215Population and housing census topics 215

4.243. If the topic needs to be introduced into the census, information should be collected

for all the marital status categories of women for whom data on children born alive are col

lected. In countries in which current births to mothers at ages below 15 years are statistically

signiﬁcant, the age limit for the investigation of current fertility may be lowered to include

mothers at appropriate younger ages.

5.5. Deaths among children born in the past 12 months

4.244. Deaths among children born in the past 12 months refers to the number of deaths

that occurred among the live births within the 12 months preceding the census reported for

the woman concerned. Hence, the topic should be investigated only if live births within this

period are also investigated.

4.245. It is recommended that information on the topic be derived from a pair of census

questions on “date of birth of last child born alive” and the follow-up question about “whether

the child is still alive” (see paragraph 4.240). Although this pair of questions does not pro

duce a valid estimate of the infant mortality rate (since the numerator excludes infant deaths

occurring below age 1 in the past 12 months among children born 1-2 years before the census

date), it can provide useful information on diﬀerences in child survival by age of mother or

other socioeconomic characteristics.

4.246. e information needs to be collected only for women for whom at least one live birth

during the reference period was reported.

5.6. Age, date or duration of ﬁrst marriage

4.247. Date of ﬁrst marriage comprises the day, month and year when the ﬁrst marriage took

place. In countries where date of ﬁrst marriage is diﬃcult to obtain, it is advisable to collect

information on age at marriage or on how many years ago the marriage took place (duration

of marriage). e information should relate to all types of marriages such as contractual ﬁrst

marriages and de facto unions, customary marriages and religious marriages.

4.248. For women who are widowed, separated or divorced at the time of the census, infor

mation on the “date of/age at/number of years since dissolution of ﬁrst marriage” should be

collected. Information on dissolution of ﬁrst marriage (if pertinent) provides data necessary

to calculate “duration of ﬁrst marriage” as a derived topic at the data-processing stage. In

countries in which duration of marriage is reported more reliably than age, tabulations of

children ever born by duration of marriage yield better fertility estimates than those based on

data on children born alive classiﬁed by age of the woman.

130

Data on duration of marriage

can be obtained by subtracting the age at marriage from the current age, or directly from the

number of years elapsed since the marriage took place.

5.7. Age of mother at birth of (date or time since) ﬁrst child born alive

131

4.249. Date of ﬁrst birth comprises the day, month and year when the woman’s ﬁrst live birth

took place. In countries where date of ﬁrst birth is diﬃcult to obtain, it is advisable to collect

information on age of mother at ﬁrst birth or on how many years ago the ﬁrst birth took place

(time since ﬁrst birth). In countries in which time since ﬁrst birth is reported more reliably

than age, tabulations of children ever born and children surviving by time since ﬁrst birth

yield more timely child mortality estimates than those based on data on children born alive

classiﬁed by age of the woman.

132

If the topic is included in the census, information should

be obtained for each woman who has had at least one child born alive.

130

Manual X: Indirect Techniques

for Demographic Estimation,

Population Studies, No. 81

( UnitedNations Publication,

Sales No. E.83.XIII.2), chapter II,

section D, available from

www.un.org/esa/population

/publications/Manual_X

/Manual_X.htm; and Handbook

on the Collection of Fertility

and Mortality Data, Studies in

Methods Series F, No.92 (United

Nations publication, Sales No.

E.03.XVII.11), chapterV, section D,

available from http://unstats

.un.org/unsd/publication

/SeriesF/SeriesF_92E.pdf.

131

Ibid., chapter II, section B.3.

132

See K. Hill, “Indirect Estimation of

Child Mortality” in Tools for Demo-

graphic Estimation, T.A.Moultrie,

R.E. Dorrington, A.G. Hill, K. Hill,

I.M. Timæus and B. Zaba, eds.

(Paris: International Union for the

Scientiﬁc Study of Population,

2013), available from

http://demographicestimation

.iussp.org/content/indirect

-estimation-child-mortality;

and J.K. Rajaratnam, , L.N. Tran,

A.D.Lopez, and C.J.L. Murray,

“Measuring under-Five Mortality:

Validation of New Low-Cost Meth-

ods, PLoS Med 7(4) (2013), available

from http://demographicestima

tion.iussp.org/content/indirect

-estimation-child-mortality.

Principles and Recommendations for Population and Housing Censuses, Revision 3216

5.8. Household deaths in the past 12 months

133

(core topic)

4.250. Information on household deaths in the past 12 months classiﬁed by sex of deceased

and age at death is used to estimate the level and pattern of mortality in countries that lack

satisfactory continuous death statistics from civil registration. In order for estimation derived

from this item to be reliable, it is important that all deaths to household members occurring

during the 12 months preceding enumeration be reported as completely and as accurately as

possible. Typically, reports of deaths in censuses underestimate the overall number of deaths

if only because some deaths result in the disintegration of households so that household sur

vivors, if any, may not report their occurrence (in particular, deaths of persons living alone at

the time of death are unlikely to be reported). Nevertheless, provided that there are no serious

errors in the reporting of age at death, estimates of completeness of death reporting can be

derived via indirect estimation and adequate mortality estimates obtained.

134

4.251. Ideally, information on mortality should be collected for each household in terms of

the total number of deaths in the 12-month period prior to the census date. For each deceased

person reported, name, age, sex and date (day, month and year) of death should also be col

lected. Care should be taken to clearly specify the reference period to the respondent so as

to avoid errors due to its misinterpretation. For example, a precise reference period could be

deﬁned in terms of a festive or historic date for each country.

4.252. When information is collected on household deaths in the previous 12 months (or

some other reference period), countries may wish to ask a pair of follow-up questions concern

ing cause of death. After ascertaining the name, age and sex of the deceased person and date

of death, two additional questions could be asked:

(a) Was the death due to an accident, violence, homicide or suicide?

(b) If the deceased was a woman aged 15

135

to 49, did the death occur while she was

pregnant or during childbirth or during the six weeks after the end of pregnancy?

4.253. Data derived from such questions can help to assess trends in levels, and some causes,

of adult mortality. At the data-processing stage, reported deaths can be tabulated accord

ing to broad categories of cause of death: external, pregnancy-related, other and unknown.

Ignoring the “unknown” responses, both external and pregnancy-related deaths can provide

valuable information in countries where no other sources of information to systematically

obtain causes of death are available. Of course, such information is approximate and must be

interpreted with caution after careful evaluation and often adjustment. Nevertheless, using

these simple questions should make it possible to derive some useful information about major

trends in mortality that are otherwise diﬃcult to obtain.

4.254. ere is no universal agreement about the feasibility of collecting reliable cause of

death information as part of a population and housing census. More research is needed on

both the feasibility and methods of collecting cause of death information as part of a national

census.

5.9. Maternal or paternal orphanhood

136

4.255. Some countries may also wish to collect information on maternal or paternal orphan-

hood in another attempt to ascertain the level and patterns of mortality in the population.

Census data from these two topics are intended for indirect estimation of mortality by sex.

Estimates are based on the proportion of persons classiﬁed by age whose natural mothers or

fathers are still alive at the time of the census.

4.256. For the collection of information on orphanhood, two direct questions should be

asked, regardless of whether or not the mother and father are enumerated in the same house

hold, namely:

133

See Handbook on the Collection of

Fertility and Mortality Data, Stud-

ies in Methods, Series F, No. 92

(United Nations publication, Sales

No. E.03.XVII.11), available from

http://unstats.un.org/unsd

/publication/SeriesF/SeriesF_92E.

pdf; Methods for Estimating Adult

Mortality (United Nations publica-

tion ESA/P/WP.175), available from

www.un.org/esa/population

/techcoop/DemEst/methods

_adultmort/methods_adultmort

.html; and Rob E. Dorrington,

“The Brass Growth Balance Meth-

od and the Preston-Coale Method

for One Census, and the General-

ized Growth Balance Method and

Synthetic Extinct Generations

Methods Upon the Availability

of Deaths from Two Censuses”, in

Tools for Demographic Estimation,

T.A. Moultrie, R.E. Dorrington,

A.G.Hill, K. Hill, I.M. Timæus and

B.Zaba, eds. (International Union

for the Scientiﬁc Study of Popula-

tion, 2013), available from http://

demographicestimation.iussp.org.

134

See chapter 4 on methods for

data evaluation and adjust-

ment in WHO, WHO Guidance for

Measuring Maternal Mortality from

a Census (Geneva, World Health

Organization, 2013), available

from http://apps.who.int/iris/bit

stream/10665/87982/1/97892415

06113_eng.pdf; and T.A. Moultrie,

R.E. Dorrington, A.G. Hill, K.Hill,

I.M. Timæus and B. Zaba, eds.,

Tools for Demographic Estima-

tion (International Union for the

Scientiﬁc Study of Population,

2013), available from http://demo

graphicestimation.iussp.org.

135

It may be appropriate in some

countries to reduce the lower age

limit by several years.

136

For methodological details

on the uses of the data,

see I.M. Timæus, “Indirect

estimation of adult mortality

from orphanhood” in Tools for

Demographic Estimation,

T.A. Moultrie, R.E. Dorrington,

A.G. Hill, K. Hill, I.M. Timæus

and B. Zaba, eds. (International

Union for the Scientiﬁc Study of

Population, 2013), available from

http://demographicestimation

.iussp.org/content/indirect

-adult-mortality-orphanhood);

217Population and housing census topics 217

(a) Whether or not the natural mother of the person enumerated in the household

is still alive at the time of the census;

(b) Whether or not the natural father of the person enumerated in the household is

still alive at the time of the census.

e investigation should secure information on biological parents. us, care should

be taken to exclude adopting and fostering parents. It should be kept in mind, however, that

overcounting may occur in the case of parents with more than one surviving child among

the respondents, particularly in high fertility societies.

4.257. It is preferable for these questions to be collected from every person in the household

regardless of age (not just children under 18, which would otherwise make the information

useless for estimating adult mortality). Not only is this important for estimating mortality at

older ages, but also for estimating the extent of age exaggeration at the older ages. Whenever

the context allows, the date of death should be collected to help to improve knowledge of the

timing of death, and in other contexts a simple follow-up question about whether the parent

was still alive ﬁve years ago can help to narrow down the timing of death and to improve adult

mortality measurement for recent years by analysing these data as successive cross-sectional

enquiries.

137

6. Educational characteristics

6.1. Literacy (core topic)

4.258. Literacy has historically been deﬁned as the ability both to read and to write, distin

guishing between “literate” and “illiterate” people. A literate person is one who can both

read and write, with understanding, a short, simple statement on his or her everyday life. An

illiterate person is one who cannot, with understanding, both read and write such a statement.

Hence, a person capable of reading and writing only ﬁgures and his or her own name should

be considered illiterate, as should a person who can read but not write as well as one who

can read and write only a ritual phrase that has been memorized. However, a more modern

understanding referring to literacy as a continuum of skills, levels, domains of application

and functionality is now widely accepted.

4.259. e notion of literacy applies to any language insofar as it exists in written form.

In multilingual countries, the census questionnaire may also enquire into the languages in

which a person can read and write. Such information can be essential for the determination

of educational policy. is item would, therefore, be a useful additional subject of enquiry.

4.260. It is preferable that data on literacy be collected for all persons 10 years of age and over.

In a number of countries, however, some children may only become literate through school

between the ages of 10 and 14 years. e literacy rate for this age group may be misleading.

erefore, in an international comparison of literacy, data on literacy should be tabulated for

all persons 15 years of age and over. Where countries collect the data for younger persons,

the tabulations on literacy should at least distinguish between persons under 15 years of age

and those 15 years of age and over.

4.261. Straightforward operational criteria and instructions for collecting literacy statistics

should be clearly established on the basis of the concept given in paragraph 4.258, and

applied during census taking.

138

Accordingly, although data on literacy should be collected

so as to distinguish between persons who are literate and those who are illiterate, considera

tion should be given to distinguishing broad levels of literacy skills. Simple questions with

response categories that reﬂect diﬀerent levels of literacy skills should be used. In addition,

since literacy is an applied skill, it needs to be measured in relation to a particular task, such

as reading, with understanding, personal letters and newspapers or magazines, or writing a

137

See I.M. Timæus, “Indirect

estimation from orphanhood in

multiple inquiries”, in Tools for

Demographic Estimation, T.A.

Moultrie, R.E. Dorrington, A.G.

Hill, K. Hill, I.M. Timæus and B.

Zaba, eds. (International Union

for the Scientiﬁc Study of Popula-

tion, 2013), available from http://

demographicestimation

.iussp.org/content/indirect-adult

-mortality-orphanhood.

138

Depending on the need for

small-area data and the circum-

stances in a country, literacy

may best be measured through

surveys.

and Methods for Estimating

Adult Mortality (United Nations

publication ESA/P/WP.175),

available from www.un.org/esa

/population/techcoop/DemEst

/methods_adultmort/methods

_adultmort.html.

Principles and Recommendations for Population and Housing Censuses, Revision 3218

personal letter or message. Respondents may be able to do so easily, with diﬃculty or not

at all, reﬂecting the diﬀerent levels of literacy skills. Reading and writing may be measured

separately to simplify the questions.

4.262. It would be preferable to use standardized questions, harmonized across countries to

ensure comparability. e United Nations Educational, Scientiﬁc and Cultural Organization

(UNESCO) has developed a reference database of model questions. In addition, UNESCO

recommends that literacy tests should be administered in order to verify as well as improve the

quality of literacy data. Nevertheless, administering a literacy test to all household members

in the course of enumeration may prove impractical and aﬀect participation, therefore limit

ing the utility of the results. Instead, administering such a test to a sample of respondents

may be considered either in the census itself or in a targeted post-enumeration follow-up

survey. Some countries have regularly used simple self-assessment questions within a census

to provide an indication of literacy rates at the small-area level. An evaluation of the quality

of statistics should be provided with census statistics on literacy.

4.263. e collection and tabulation of statistics on literacy during the population census

should not be based on any assumed linkages between literacy, school attendance and edu

cational attainment. In operational terms, this means systematically enquiring about the

literacy status of each household member irrespective of school attendance or highest grade

or level completed.

4.264. e literacy question currently varies across countries and, as a result, the data based

on it are not always internationally comparable. Literacy should not be derived as an edu

cational attainment proxy because although the two are related, there are substantial diﬀer-

ences. For example, there are numerous cases where people leave school with only partial

literacy skills, or lose them because of a lack of practice. erefore educational attainment is

not a good proxy measure of literacy skills.

6.2. School attendance (core topic)

4.265. School attendance is deﬁned as regular attendance at any regular accredited educa

tional institution or programme, public or private, for organized learning at any level of

education at the time of the census or, if the census is taken during the vacation period, at

the end of the school year or during the previous school year. According to the International

Standard Classiﬁcation of Education (ISCED), education is taken to comprise all institu

tionalized, intentional and planned activities designed to meet learning needs. Instruction

in particular skills that is not part of the recognized educational structure of the country (for

example, in-service training courses in factories) is not normally considered “school attend

ance” for census purposes.

4.266. Information on school attendance should, in principle, be collected for persons of all

ages. It relates in particular to the population of oﬃcial school age, which ranges in general

from 5 to 29 years of age but can vary from country to country depending on the national

education structure. In the case where data collection is extended to cover attendance in pre-

primary education or other systematic educational and training programmes organized for

adults in productive and service enterprises (such as the in-service training courses mentioned

in paragraph 4.265), community-based organizations and other non-educational institutions,

the age range may be adjusted as appropriate.

4.267. Data on school attendance should be cross-classiﬁed with data on educational attain

ment, according to the person’s current level and grade (see paragraph 4.272). is cross-

classiﬁcation can provide useful information on the correspondence between age and level

or grade of educational attainment for persons attending school.

219Population and housing census topics 219

4.268. e issue surrounding the number of out-of-school children has grown in importance

within recent decades, particularly within the context of the UNESCO Education for All

goal with regard to achieving universal primary education. e target year for Education for

All was 2015, and new goals for the post-2015 period were not yet deﬁned at the time this

document was prepared. e census oﬀers an opportunity to measure the number of “out-

of-school” (reciprocal of attendance) or “ever-in-school” children.

4.269. ere is a diﬀerence between “attending school” and “enrolled in school”, thus results

from censuses and administrative data may diﬀer. A child can be enrolled in school but not

necessarily be attending. It is recommended that these concepts be clearly deﬁned so that

countries can determine which variable they wish to collect via the census.

4.270. It is also recommended that Member States consider the need for internationally

harmonized questions in order to measure school attendance and school enrolment.

4.271. For purposes of international comparison, data on school attendance should be pre

sented by the ISCED-P (or ISCED-Programmes) levels listed below, which are used for the

classiﬁcation of education programmes in ISCED 2011. Correspondence between a national

education system and ISCED can be established through mapping of national education

programmes to the ISCED classiﬁcation.

139

ISCED level 0: Early childhood education

ISCED level 1: Primary education

ISCED level 2: Lower secondary education

ISCED level 3: Upper secondary education

ISCED level 4: Post-secondary non-tertiary education

ISCED level 5: Short-cycle tertiary education

ISCED level 6: Bachelor’s or equivalent level

ISCED level 7: Master’s or equivalent level

ISCED level 8: Doctoral or equivalent level

6.3. Educational attainment (core topic)

4.272. e recommendations on “educational attainment” (see paragraph 4.273) and “edu-

cational qualiﬁcations” (see paragraph 4.287) make use of categories of the 2011 revision of

ISCED, issued by UNESCO.

140

In accordance with national conditions and requirements,

many countries can continue to apply national classiﬁcations of levels and grades of education

and of ﬁelds of education in collecting and tabulating statistics from population censuses.

Special attention needs to be paid to establishing appropriate level or grade equivalence for

persons who have received education under a diﬀerent or foreign educational system. ese

national classiﬁcations, however, should be able to be converted or mapped to the ISCED

2011 classiﬁcation system, this typically being achieved during post-census processing.

4.273. Educational attainment is deﬁned as the highest ISCED level successfully completed

by an individual. Educational attainment is usually measured with respect to the highest

education programme successfully completed, which is typically certiﬁed by a recognized

qualiﬁcation. Some countries may also ﬁnd it useful to present data on educational attain

ment in terms of the highest grade completed. For international purposes a “grade” is a spe-

ciﬁc stage of instruction usually covered in the course of an academic year. Information on

educational attainment should preferably be collected for all persons 5 years of age and over.

4.274. To produce statistics on educational attainment, a classiﬁcation is needed that indi

cates the qualiﬁcations certifying the successful completion of primary, secondary and post-

secondary education. Since the educational structure may have changed over time, it is neces

sary to make provisions for persons educated at a time when the national educational system

139

The UNESCO Institute for Statis-

tics maintains a database with

ISCED mappings at www.uis

.unesco.org/ISCED.

140

UNESCO Institute for Statistics,

International Standard

Classiﬁcation of Education: ISCED

2011, (Montreal, UIS, 2012),

available from www.uis.unesco

.org/Education/Documents

/isced-2011-en.pdf.

Principles and Recommendations for Population and Housing Censuses, Revision 3220

diﬀered from that in place at the time of the census. In addition to focusing attention on the

collection of educational attainment data, enumerator instructions, coding and data process

ing need to be designed in a way that will take account of any changes in the educational

system of a country over the years and of those educated in another country, as well as those

educated in the current system.

4.275. Information collected on the highest level of education successfully completed by each

individual, typically certiﬁed by a recognized qualiﬁcation, facilitates ﬂexible regrouping of

the data according to various kinds of aggregation. Recognized intermediate qualiﬁcations

are classiﬁed at a lower level than the programme itself. Information on intermediate quali

ﬁcations or on the highest grade completed can be used to distinguish between persons who

did and persons who did not complete each level of education.

4.276. For international comparison, data from the population census are needed for all lev

els of education deﬁned in ISCED. To the extent possible, countries should classify statistics

on educational attainment by the individual ISCED-A (or ISCED-Attainment) levels listed

below, which are used for the classiﬁcation of educational attainment in ISCED 2011 (or by

their equivalent as set forth according to the national classiﬁcation of levels of education):

ISCED level 0: Less than primary education

ISCED level 1: Primary education

ISCED level 2: Lower secondary education

ISCED level 3: Upper secondary education

ISCED level 4: Post-secondary non-tertiary education

ISCED level 5: Short-cycle tertiary education

ISCED level 6: Bachelor’s or equivalent level

ISCED level 7: Master’s or equivalent level

ISCED level 8: Doctoral or equivalent level

4.277. For the classiﬁcation of educational attainment, ISCED level 0 has a diﬀerent meaning

in ISCED 2011 than for the classiﬁcation of education programmes (see paragraph 4.271): it

means not having successfully completed ISCED level 1. is includes individuals who have

never attended an education programme, who have attended some early childhood educa

tion (deﬁned as ISCED level 0 in the classiﬁcation of education programmes), or who have

attended some primary education but have not successfully completed ISCED level 1. Any

diﬀerences between national and international deﬁnitions and classiﬁcations of education

should be explained in the census publications in order to facilitate comparison and analysis.

4.278. Countries could consider asking a question that captures levels of education not suc

cessfully completed, should this be of interest to policymakers or other users. is could be

in the form of a direct question asking if a person has some education at the relevant level

or via a question asking the last grade or year completed from any given level of education.

4.279. Data on school attendance, educational attainment and literacy status should be col

lected and tabulated separately and independently of each other, without (as elaborated in

paragraph 4.263) any assumption of linkages between them.

4.280. In order to ensure continued and improved international comparability of census

data by level of education, it is recommended that countries continue to ensure that the

educational attainment variable can be mapped into the ISCED 2011 classiﬁcation. is is

typically achieved in post-census processing.

221Population and housing census topics 221

6.4. Field of education and educational qualiﬁcations

(a) Field of education and training

4.281. Information on persons by level of education and ﬁeld of education and training is

important for examining the match between the supply and demand for qualiﬁed workers

with speciﬁc specializations within the labour market. It is equally important for planning

and regulating the production capacities of diﬀerent levels, types and branches of educational

institutions and training programmes.

4.282. A question on ﬁeld of education and training needs to be addressed to persons 15 years

of age and over who attended at least one grade in secondary education, or who attended other

organized educational and training programmes at equivalent levels.

4.283. e ISCED Fields of Education and Training 2013 (ISCED-F 2013) distinguishes

between broad ﬁelds (two-digit codes), narrow ﬁelds (three-digit codes) and detailed ﬁelds

(four-digit codes) of education and training.

141

e broad ﬁelds are listed here:

00 Generic programmes and qualifications

01 Education

02 Arts and humanities

03 Social sciences, journalism and information

04 Business, administration and law

05 Natural sciences, mathematics and statistics

06 Information and communication technologies (ICTs)

07 Engineering, manufacturing and construction

08 Agriculture, forestry, fisheries and veterinary

09 Health and welfare

10 Services

99 Unknown

4.284. Countries may wish to consider collecting data on narrow and detailed ﬁelds of edu-

cation and training, not only on the broad ﬁelds. For this, countries should make use of the

classiﬁcation and coding of ﬁelds of education and training of ISCED.

4.285. Countries coding ﬁeld of education and training according to a national classiﬁca

tion should establish correspondence with ISCED, either through double coding or through

conversion from the detailed national classiﬁcation to ISCED. A problem may arise in iden

tifying the exact ﬁelds of education and training of persons with interdisciplinary or multi-

disciplinary ﬁelds of specialization. In these cases it is recommended that countries follow

the procedure of identifying the major or principal ﬁeld of education and training of those

with multidisciplinary specialization.

4.286. In order to ensure continued and improved international comparability of census data

by ﬁeld of education and training, it is recommended that the classiﬁcation structure for the

ﬁelds of education and training continue to be based on the most recent version of ISCED.

(b) Educational qualiﬁcations

4.287. Educational qualiﬁcation is the oﬃcial conﬁrmation, usually in the form of a docu

ment, certifying the successful completion of an education programme or a stage of a pro-

gramme. Qualiﬁcations can be obtained through (a) successful completion of a full education

programme; (b) successful completion of a stage of an education programme (intermediate

qualiﬁcations); or (c) validation of acquired knowledge, skills and competencies, independent

of participation in an education programme.

141

UNESCO Institute for Statistics,

ISCED Fields of Education and

Training 2013 (ISCED-F 2013)

(Montreal, UIS, 2014), available

from www.uis.unesco.org

/Education/Documents

/isced-ﬁelds-of-education

-training-2013.pdf.

Principles and Recommendations for Population and Housing Censuses, Revision 3222

4.288. According to national needs, information on qualiﬁcations may be collected from

persons who have reached a certain minimum age or level of educational attainment. Such

information should refer to the title of the highest certiﬁcate, diploma or degree received.

7. Economic characteristics

7.1. Introduction

4.289. Statistics on the economic characteristics of persons are needed from population cen

suses for many reasons. Information on the productive activities of persons is vital to establish

a comprehensive picture of the economic structure of a country, and the work patterns, labour

market participation and extent of labour underutilization of its population. is informa

tion, when combined with other personal, household and dwelling characteristics collected

in the census, enables assessments of the socioeconomic situation of persons and households,

which are essential to inform the planning of a wide range of economic and social policies

and programmes related to such areas as employment creation, poverty reduction, work-life

balance, vocational education and training, provision of social security and other social ben

eﬁts, gender justice and social inclusion.

4.290. Such statistics can be obtained from other sources, such as household-based surveys or

administrative records, but these other sources have certain limitations. Household surveys,

especially labour force surveys, are particularly well suited for generating a broad range of

statistics on the economic characteristics of the population at aggregate levels, such as national

and broad regional groupings. Data obtained from labour force surveys, however, are sub

ject to sampling error and, therefore, rarely provide reliable estimates for small areas, small

population groups, or detailed groups of industries and occupations. In contrast, population

censuses can provide certain core statistics at the lowest levels of aggregation for such small

population groups and for detailed occupation and industry groups. Administrative records

may not have the same quality of occupational and industry coding, nor have the same com

prehensiveness in population or activity coverage, generally excluding productive activities

that are informal or unpaid.

4.291. e population census also provides benchmark information to which statistics from

other sources can be related. Population censuses likewise provide the sample frames for

most household-based surveys, including labour force surveys. In countries with a limited or

infrequent household survey programme, the population census may represent the main or

only source of information on the economic characteristics of the population.

4.292. In deciding which topics relating to the economic characteristics of the population to

include in the population census, countries will need to assess the existence of other sources

of statistics and their complementary uses. e aim should be to cover the core topics needed

as benchmark information for the preparation of sample frames, and to provide essential sta

tistics for small areas and small population groups, and for detailed occupation and industry

groups, as relevant in the national context.

4.293. International resolutions and guidelines to produce statistics relating to the economic

characteristics of the population are adopted by the International Conference of Labour Stat

isticians and endorsed by the Governing Body of the International Labour Organization.

142

Recommendations on topics amenable for inclusion in population censuses are discussed in

general in Box 1. e complete labour statistics standards are available from www.ilo.org

/global/statistics-and-databases/standards-and-guidelines/lang--en/index.htm.

143

142

See www.ilo.org/stat.

143

Nineteenth International

Conference of Labour

Statisticians, Resolution

Concerning Statistics of Work,

Employment and Labour

Underutilization (Geneva, 2013),

available from www.ilo.org

/global/statistics-and-databases

/meetings-and-events

/international-conference

-of-labour-statisticians/19

/WCMS_230304/lang--en

/index.htm.

223Population and housing census topics 223

7.2. Conceptual framework for work statistics

(a) Work

4.294. Measurement of the economic characteristics of the population is based on the con

ceptual framework for work statistics (see Box 1). In this framework, work is deﬁned for

reference purposes as “any activity performed by persons of any sex and age to produce goods

or to provide services for use by others or for own use”.

4.295. e concept of work is aligned with the general production boundary as deﬁned in the

System of National Accounts 2008 (2008 SNA), enabling full integration between work statis

Box 1.

New international recommendations concerning statistics of work,

employment and labour underutilization

In October 2013, the Nineteenth International Conference of Labour Statisticians adopted the

Resolution concerning statistics of work, employment and labour underutilization.

143

This reso-

lution replaced the previous international recommendations relating to the measurement

of the economically active population, employment, unemployment and underemployment

dating from 1982 (Thirteenth International Conference of Labour Statisticians) and related

guidelines.

These new standards introduced a number of important revisions, among which are a con-

ceptual framework for work statistics consistent with the System of National Accounts; guide-

lines for separately measuring different forms of work, including a more targeted definition

of employment as work for pay or profit, and for expanding the range of measures of labour

underutilization beyond the traditional unemployment. New terminology was also intro-

duced, as relevant, and terms considered to be out of date, particularly “economically active/

inactive”, were replaced with “labour force/outside the labour force.”

Important elements from the previous standards essential to the internal consistency of the

statistics remain unchanged. The refinements to the definition of employment and new

measures of labour underutilization may result, however, in breaks in the historical series

of statistics of the economically active population, employment, unemployment and under-

employment. In particular, productive activities carried out without pay, such as those listed

below, are no longer included within the scope of employment:

• Production of goods intended for own final use by the household;

• Unpaid work by apprentices, interns and trainees;

• Organization-based volunteer work;

• Direct volunteering to produce goods for other households.

Participation in these activities is now to be measured separately through the newly defined

forms of work: own-use production work, unpaid trainee work and volunteer work, respectively.

Countries are encouraged to develop their statistical system so as to cover work statistics,

including statistics on the labour force, based on their specific national needs and resources.

In the case of the measures affected by the Nineteenth International Conference of Labour

Statisticians Resolution, the updated international standards would ideally be implemented

over time, in a way that is feasible for national statistical systems. During the transition period

it is of utmost importance that the institutions and persons responsible for planning and

managing the production of statistics on the economic characteristics of the population

develop a strategic and coordinated approach that takes into account all official sources of

statistics, including the population census, labour force survey and other household-based

surveys and administrative records. Data users will need to be kept well informed of the pro-

cess, including by widely disseminating the relevant metadata and by maintaining parallel

series for a specified period following their implementation.

Principles and Recommendations for Population and Housing Censuses, Revision 3224

tics and production statistics. All work or productive activities are thus included, irrespective

of their formal or informal character or the legality of the activity. Excluded are activities that

do not involve producing goods or services (for example begging and stealing), self-care (for

example personal grooming and hygiene), and activities that cannot be performed by another

person on one’s own behalf (for example sleeping, learning and activities for own recreation).

4.296. Work can be performed in any kind of economic unit, including market units (for

example corporations, quasi-corporations and household unincorporated market enterprises);

non-market units (for example government and non-proﬁt institutions serving households);

and households that produce goods or services for own ﬁnal use by the producers.

144

4.29 7. e conceptual framework for work statistics identiﬁes ﬁve mutually exclusive forms

of work for separate measurement (see ﬁgure 3):

(a) Own-use production work, comprising production of goods and services for own

ﬁnal use;

(b) Employment work, comprising work performed in exchange for pay or proﬁt;

acquire workplace experience or skills;

(d) Volunteer work, comprising non-compulsory work performed for others without pay;

(e) Other work activities, including unpaid compulsory work performed for others,

such as community service and work by prisoners, when ordered by a court or

similar authority, and unpaid military or alternative civilian service.

4.298. During a given reference period, persons may engage in one or more forms of work

in parallel or consecutively, that is, persons may be employed, volunteering, doing unpaid

trainee work or producing for own ﬁnal use, in any combination.

4.299. To meet diﬀerent objectives, countries may measure the economic characteristics of

the population with respect to their participation in one or in several forms of work. In par

ticular, in the population census, this may include measurement of the following:

(a) Persons in employment is essential as part of the preparation of labour force statis

tics that include unemployment and other measures of labour underutilization.

It is needed to assess the labour market participation of the population and to

classify the population according to their labour force status in a short reference

period (see paragraphs 4.307-4.333).

(b) Persons in own-use production of goods is especially important in countries where

particular groups of the population engage in agriculture, ﬁshing or hunting and

gathering for own ﬁnal consumption, including for subsistence (see paragraphs

4.376-4.381), and to enable integration of the population census with the agri

cultural census (see paragraphs 1.44-1.50).

internships and traineeships may be a main mechanism of labour market entry

for particular groups such as youths or for speciﬁc occupations such as mechanics

or tailors, given their likely overall small size in the country and limited avail

ability of alternative statistical sources.

4.300. Given the need for detailed probing, measurement of participation in own-use provi

sion of services, unpaid trainee work and volunteer work is more appropriate through house-

hold surveys or, if desired, through the population census by means of a long form applied

to a subset of the population.

145

4.301. Additional information may also be collected in the population census in order to

classify the population according to their main form of work based on self-declaration, in a

short or long reference period.

146

144

System of National Accounts 2008

(United Nations publication,

Sales No. E.08.XVII.29).

145

Nineteenth International Confer-

ence of Labour Statisticians,

Resolution Concerning Statistics

of Work, Employment and Labour

Underutilization (Geneva, 2013),

paras.22(c) and 37-39.

146

Ibid, paragraph 17.

225Population and housing census topics 225

(b) Working time

4.302. e concept of working time comprises the time associated with productive or work

activities and the arrangement of this time during a speciﬁed reference period.

147

Working

time relates to each form of work.

4.303. e number of persons engaged in a given form of work provides only a very rough

estimate of the volume of work performed, particularly when the work is performed on a

part-time, casual or occasional basis. Information on working time is necessary to prepare

estimates of the volume of work or labour input for complete national production accounts.

It is also essential to support the design, monitoring and evaluation of economic, social and

labour market policies and programmes targeting labour market ﬂexibility, work-life balance

and conditions of work, including situations of underemployment due to insuﬃcient working

time (that is, time-related underemployment) and of excessive working time.

4.304. e population census can serve to provide information on two measures of working

time in particular: hours usually worked and hours actually worked. Where the census is the

only available data source it may as a minimum incorporate a single question on hours usually

worked for persons in employment (see paragraphs 4.369-4.375) and for persons in own-use

production of goods, as relevant (see paragraph 4.381).

4.305. Information on the economic characteristics of the population should in principle

cover the entire population, regardless of country of origin, citizenship or geographic loca

tion of their place of work. In practice, a lower age limit is usually set in accordance with

the conditions in the country. Where national programmes of statistics on the working-age

population or on child labour exist, the statistics derived from the population census will

serve to complement those bodies of statistics. For purposes of compiling statistics on the

working-age population, international standards recommend that countries set the lower age

limit taking into consideration the minimum age for employment and exceptions speciﬁed in

national laws or regulations, or the age of completion of compulsory schooling.

148

For compil-

ing child labour statistics, the relevant international standards identify the target population

as all persons in the 5 to 17 years age group.

149

Countries in which many children participate

in employment or in other forms of work, including in agriculture, will need to select a lower

minimum age than countries where work of children is uncommon. Census tabulations of

economic characteristics should at least distinguish between persons under 15 years of age

and those 15 years of age and over.

4.306. In general, an upper age limit is not recommended, so as to permit comprehen

sive coverage of work activities of the adult population and to examine transitions between

147

Eighteenth International

Conference of Labour Statisti-

cians, Resolution Concerning the

Measurement of Working Time,

(Geneva, 2008).

148

Nineteenth International Confer-

ence of Labour Statisticians,

Resolution Concerning Statistics

Of Work, Employment and Labour

Underutilization (Geneva, 2013),

para. 65.

149

Eighteenth International Confer-

ence of Labour Statisticians,

Resolution Concerning Statistics of

Child Labour (Geneva, 2008).

Figure 3.

Forms of work and the System of National Accounts 2008

Intended destina-

tion of production

for own

ﬁnal use

for use

by others

Forms of work

Own-use

production work

Employment

(work for pay or proﬁt)

Unpaid

trainee work

Other work

activities

Volunteer work

services

goods

in market and

non-market units

in households producing

goods services

Relation to

2008 SNA

Activities within the SNA production boundary

Activities inside the SNA general production boundary

Principles and Recommendations for Population and Housing Censuses, Revision 3226

employment and retirement. Many people continue to be engaged in employment and in

other forms of work beyond retirement age, and the numbers involved are likely to increase

as a result of factors associated with the “ageing” of the population. Countries may, however,

wish to balance the cost of collecting and processing information relating to the productive

activities of older persons (those aged 75 years or more) and the additional response burden

imposed on them against the signiﬁcance and reliability of the information provided.

7.3. Labour force status (core topic)

4.3 07. A classiﬁcation of persons by their labour force status provides important information

about their relation to the labour market, in particular to work for pay or proﬁt, in a short

reference period.

4.308. Persons may be classiﬁed in a short reference period according to their labour force

status as being employed, unemployed, or outside the labour force as deﬁned below in para

graphs 4.312-4.333. e three categories of labour force status are mutually exclusive and

exhaustive. While even during a short period persons may be engaged in multiple activi

ties, to establish their labour force status, priority is given to employment over other forms

of work, and over unemployment; and to unemployment over outside the labour force (see

ﬁgure 4). us, a volunteer worker who also has a part-time employee job should be classiﬁed

as employed, a student who is also seeking and available for employment should be classiﬁed as

unemployed, and a person who has a part-time job working only a few hours for pay and who is

also seeking another job should be classiﬁed as employed. e sum of persons in employment

plus persons in unemployment comprises the labour force.

4.309. e labour force status of persons is established with regard to a short reference period

of seven days or one week, which may be the last seven days prior to the speciﬁed census

day, the last completed calendar week or a speciﬁed recent ﬁxed week. For comparability

purposes, it is particularly useful to apply the same short reference period for the census as

for the national labour force survey, if any. is short reference period serves to provide a

snapshot picture of labour market participation in the country around the time of the census.

As such, the labour force (that is, persons in employment plus persons in unemployment)

reﬂects the supply of labour for the production of goods and services in exchange for pay or

proﬁt at a speciﬁed point in time. Seasonal variations in employment and unemployment

levels, which may be signiﬁcant both in industrialized and in developing economies, will not

be captured. Assessments of such temporal variations in work patterns are more adequately

captured through sub-annual household surveys (for example monthly, quarterly).

4.310. Depending on the way the relevant parts of the census questionnaire have been con

structed, the determination of the labour force status of a person may be inﬂuenced by

respondents’ or enumerators’ subjective understanding of the concepts of employment and

unemployment. In this regard, particular attention should be given to special groups for

which the determination of labour force status may be diﬃcult. ese groups include youths,

women and older persons after the normal age of retirement, in particular those working as

contributing family members. eir participation in employment and job search activities

is frequently overlooked and needs close attention. In particular, the common notion that

women are generally engaged in homemaking duties, or cultural perceptions relating to

gender roles, can result in serious omissions with respect to measuring women’s participation

in employment and job search activities. To reduce underreporting, enumerators need to be

explicitly instructed, or the questionnaires speciﬁcally designed, to ask about the possible jobs,

including part-time, casual, temporary and informal jobs, or job search activities of every

woman and man above the speciﬁed age in the household.

227Population and housing census topics 227

4.311. e addition of probing questions in an interview, or more detailed questions in a self-

administered questionnaire, may lengthen the time required to complete the questionnaire

and increase the cost of the census. Accordingly, it will be necessary to balance the gains in

terms of minimizing response errors when such questions are used against the added costs

associated with their inclusion. Given the importance of reliable data on labour force status,

however, serious consideration should be given to minimizing classiﬁcation errors. To this

end, the training of enumerators should highlight likely sources of omission or gender bias

leading to underestimation of participation in employment.

(a) Employed persons

4.312. Employed persons are all those above the speciﬁed age who during a short reference

period of seven days or one week were engaged in any activity to produce goods or provide

services for pay or proﬁt. e notion “for pay or proﬁt” refers to work done as part of a trans

action in exchange for remuneration payable in the form of wages or salaries for time worked

or work done or in the form of proﬁts derived through market transactions from the goods

and services produced. It includes remuneration in cash or in kind, whether actually received

or not, payable directly to the person performing the work or indirectly to a household or

family member.

4.313. Two categories of persons in employment are (a) employed persons “at work”, that is,

who worked for pay or proﬁt for at least one hour; and (b) employed persons “not at work”

due to working-time arrangements (such as shift work, ﬂexitime and compensatory leave for

overtime) or to “temporary absence” from a job for pay or proﬁt.

4.314. Use of the one-hour criterion serves to ensure coverage of all types of jobs engaged in,

including part-time, temporary or casual jobs, thereby supporting identiﬁcation of all persons

Population above speciﬁed age (a + b + c)

Worked for pay/proﬁt, for at least 1 hour

in a short reference period (7 days/1 week)

Had paid job/business

from which was

temporarily absent

Did not looked for work

for pay/proﬁt in

last 4 weeks/1 month

Looked for work

for pay/proﬁt in

last 4 weeks/1 month

Did not have a

paid job/business

Did not work for pay/proﬁt

in a short reference period (7 days/1 week)

Future starters

Not available

to start work

for pay/proﬁt

Available

to start work

for pay/proﬁt

(a) Employed

(b) Unemployed

Figure 4.

Classiﬁcation of working age population by labour force status

Principles and Recommendations for Population and Housing Censuses, Revision 3228

in employment and analysis of their working conditions. is criterion is also essential in

order to ensure that unemployed persons refer to those without any employment, who are

seeking and available for work for pay or proﬁt. Moreover, this criterion is a prerequisite for

the consistency of employment statistics with national accounts data on production. When

information on working time is also collected (see paragraphs 4.369-4.375), it is recom

mended that employed persons be classiﬁed by speciﬁed bands of working time so as to enable

identiﬁcation of persons with both short and excessive working time.

4.315. Persons on “temporary absence” from a job, including as employees or self-employed,

should be considered as in employment, provided that they were “not at work” for a short

duration and maintained a job attachment during the absence. e existence of a job attach

ment should be established on the basis of the reason for the absence and, in the case of certain

reasons, the continued receipt of remuneration or the total duration of the absence (in general

not greater than three months).

(a) Reasons for absence where job attachment is generally maintained and thus do

not require further probing include sick leave due to own illness or injury (includ

ing occupational); public holidays, vacation or annual leave; and periods of mater-

nity or paternity leave as speciﬁed by legislation.

(b) Reasons for absence requiring further assessment of continued receipt of remu

neration or total duration include parental leave, educational leave, care for oth-

ers, other personal absences, strikes or lockouts, reduction in economic activity

(for example temporary lay-oﬀ, slack work), disorganization or suspension of

work (for example due to bad weather, mechanical, electrical or communication

breakdown, problems with ICT, and shortage of raw materials or fuels).

Treatment of speciﬁc groups

4.316. According to international standards, the following groups of persons should be clas

siﬁed as in employment:

(a) Persons with a job for pay or proﬁt who, during the reference period, were on

training or skills enhancement activities required by their job or for another job

in the same economic unit;

(b) Apprentices, interns or trainees who work for pay in cash or in kind;

(d) Persons who work in their own economic units to produce goods intended mainly

for sale or barter, even if part of the output is consumed by the household or family;

(e) Persons with seasonal jobs during the oﬀ season, if they continue to perform some

tasks and duties of the job, excluding, however, fulﬁlment of legal or administra

tive obligations (for example pay taxes);

(f ) Regular members of the armed forces and persons on military or alternative civil

ian service who perform this work for pay in cash or in kind.

4.317. Persons who either work in a market unit operated by a family member living in the

same or in another household (that is, contributing family workers) or perform tasks or duties

of an employee job held by a family member living in the same or in another household should

also be classiﬁed as in employment. ese groups of workers are included in employment,

regardless of the number of hours actually worked, as they contribute their labour to produce

goods and services for pay or proﬁt, payable to the household or family.

4.318. In accordance with the priority rule to establish their labour force status (see para

graph 4.308), persons who during the reference period were primarily students, homemakers,

229Population and housing census topics 229

pensioners, registered unemployed, or engaged in other forms of work, and at the same time

were engaged in employment, as deﬁned above, should be classiﬁed as in employment.

4.319. Excluded from employment are:

(a) Apprentices, interns and trainees who work without pay in cash or in kind (that

is, unpaid trainee work);

(b) Participants in skills training or retraining schemes within employment promotion

programmes, when not engaged in the production process of an economic unit;

a government social beneﬁt such as unemployment insurance;

(d) Persons with seasonal jobs during the oﬀ season, if they cease to perform the tasks

and duties of the job;

(e) Persons who retain a right to return to the same economic unit but who were

absent for reasons speciﬁed in paragraph 4.315(b), when the total duration of the

absence exceeds the speciﬁed threshold or if the test of receipt of remuneration is

not fulﬁlled;

(f ) Persons on indeﬁnite lay-oﬀ who do not have an assurance of return to employ

ment with the same economic unit;

(g) Persons who work to produce goods intended mainly or exclusively for consump

tion or use by the household or family, even if a surplus or part of the output is

sold or bartered (that is, own-use production of goods, see paragraphs 4.376);

(h) Household members who provide unpaid services for consumption or use by their

household (that is, own-use provision of services);

(i) Persons who work voluntarily and without pay to produce goods or services

through or for other economic units, including market, non-market units and

households (that is, volunteer work).

4.320. Information should be given in the census reports describing how the above-men

tioned groups and other relevant groups were treated. Consideration should also be given to

the desirability of identifying some of the groups (for example paid apprentices, interns and

trainees) separately in tabulations.

(b) Unemployed persons

4.321. Unemployed persons are all those above the speciﬁed age who (a) were not in employ

ment, (b) carried out activities to seek employment during a speciﬁed recent period and

4.322. To be classiﬁed as unemployed, a person must satisfy all of the three criteria, where:

(a) “Not in employment” (that is, not engaged in work for pay or proﬁt) is assessed

with respect to the short reference period for the measurement of employment as

deﬁned in paragraph 4.312.

(b) To “seek employment” refers to any activity when carried out, during a speciﬁed

recent period comprising the last four weeks prior to enumeration or calendar

month, for the purpose of ﬁnding a job or setting up a business or agricultural

undertaking. is includes also part-time, informal, temporary, seasonal or

casual employment, paid apprenticeships, internships or traineeships, within

the national territory or abroad. Examples of such activities are arranging for

ﬁnancial resources; applying for permits or licences; looking for land, premises,

machinery, supplies or farming inputs; seeking the assistance of friends, relatives

or other types of intermediaries; registering with or contacting public or private

Principles and Recommendations for Population and Housing Censuses, Revision 3230

employment services; applying to employers directly, or checking at worksites,

farms, factory gates, markets or other assembly places; placing or answering news

paper or online job advertisements; and placing or updating résumés on profes-

sional or social networking sites online.

assessed with respect to the same short reference period that is used to measure

employment. Depending on national circumstances, the reference period may be

extended to include a short subsequent period not exceeding two weeks in total,

so as to ensure adequate coverage of unemployment situations among diﬀerent

population groups.

4.323. Unemployment has been one of the most widely used measures of labour underutiliza

tion. However, it only captures persons in situations of complete lack of work for pay or proﬁt,

and where opportunities for job search exist. In circumstances where there are few chan

nels for seeking employment or where labour markets are limited in scope, or when labour

absorption is inadequate, unemployment will not capture fully all persons with an unmet

need for employment, as persons will take any available jobs, create their own jobs, often as

own-account workers, become discouraged, or engage in production of goods for own ﬁnal

use (for example, subsistence agriculture or ﬁshing). Additional measures of underutilized

labour include the potential labour force,

150

deﬁned in paragraph 4.330, and persons in time-

related underemployment.

151

Separate identiﬁcation of these groups of persons supports better

assessment of the diﬀerent types of underutilization aﬀecting labour markets across settings,

and for more targeted policymaking.

4.324. It may be useful to distinguish ﬁrst-time jobseekers, who have never worked before,

from other jobseekers in the classiﬁcation of the unemployed. Such a separation would be

useful for policy purposes as well as in improving the international comparability of employ

ment statistics. To do so, however, may require an additional question regarding previous

work experience, which may impose too much of a burden for a population census.

Treatment of speciﬁc groups

4.325. Also classiﬁed as unemployed according to international standards are:

(a) Future starters, deﬁned as persons “not in employment” and “currently available”

who did not “seek employment” because they had already made arrangements to

start a job within a short subsequent period, set according to the general length

of waiting time for starting a new job in the national context but generally not

greater than three months;

(b) Participants in skills training or retraining schemes within employment promo

tion programmes, who, on that basis, were “not in employment”, not “currently

available” and did not “seek employment” because they had a job oﬀer to start

within a short subsequent period, generally not greater than three months;

to work for pay or proﬁt but who were still waiting for the opportunity to leave.

4.326. In accordance with the priority rule to establish their labour force status (see para

graph 4.308), persons who during the reference period were mainly students, homemakers,

pensioners, registered unemployed or engaged in forms of work other than employment (for

example, own-use production work, volunteer work), and who at the same time were “not in

employment”, carried out activities to “seek employment” and were “currently available”, as

deﬁned above, should be classiﬁed as in unemployment. Information should be given in the

census reports on how persons in these and any other speciﬁc groups were treated.

150

Replaces the optional relaxation

of the “seeking work” criterion

in the previous International

Conference of Labour Statisti-

cians standards.

151

See Nineteenth International

Conference of Labour Statisti-

cians, Resolution Concerning

Statistics of Work, Employment

and Labour Underutilization

(Geneva, 2013).

231Population and housing census topics 231

4.327. Persons outside the labour force comprise all those who in the short reference period

were neither employed nor unemployed as deﬁned above, including persons below the mini

mum age speciﬁed for the collection of economic characteristics.

4.328. Diﬀerent classiﬁcations of persons outside the labour force may be used for analytical

purposes. Particularly useful for informing labour market and social policies and programmes

are classiﬁcations by degree of labour market attachment and by main reason for not enter

ing the labour force. ese alternative classiﬁcations can be derived from the same questions

used to identify the unemployed and may be used separately or in combination to enable

further analysis.

4.329. Persons outside the labour force may be classiﬁed by the degree of labour market attach

ment into the following groups:

(a) Unavailable jobseekers, that is, those “seeking employment” but not “currently

available”;

(b) Available potential jobseekers, that is, those not “seeking employment” but “cur

rently available”;

rently available” but who want employment;

(d) Others, that is, persons neither “seeking employment” nor “currently available”

who do not want employment.

4.330. e classiﬁcation of persons outside the labour force by degree of labour market

attachment allows identiﬁcation of the potential labour force, computed as the sum of (a) una

vailable jobseekers plus (b) available potential jobseekers. Together with unemployment, the

potential labour force is a key measure of labour underutilization, relevant both in more and

less developed settings, especially where the conventional means of seeking employment are

of limited relevance, where the labour market is largely unorganized or of limited scope, when

labour absorption is, at the time, inadequate, or where persons are largely self-employed.

4.331. Although not a part of the potential labour force, the group (c) willing non-jobseekers

represents another group of persons outside the labour force with an expressed interest in

employment and is particularly relevant for social and gender analysis in speciﬁc contexts.

4.332. Persons outside the labour force may also be classiﬁed by their main activity or reason

for not entering the labour market into the following groups. Some persons may be classiﬁ

able in more than one category. In such situations, priority should be given to the possible

categories in the following order:

(a) Attending an educational institution refers to persons outside the labour force,

who attended any regular educational institution, public or private, for system

atic instruction at any level of education, or were on temporary absence from the

institution for relevant reasons corresponding to those speciﬁed for employed

persons “not at work”.

(b) Performing unpaid household services refers to persons outside the labour force

engaged in the unpaid provision of services for their own household, such as

spouses and other relatives responsible for the care and management of the home,

children and older persons. (Domestic and personal services provided by domestic

employees working for pay in somebody else’s home are considered as employed

in line with paragraph 4.312 above).

Principles and Recommendations for Population and Housing Censuses, Revision 3232

receive income from property or investments, interests, rents, royalties or pensions

from former employment.

(d) Other reasons refers to all persons outside the labour force who do not fall into

any of the above categories (for example, children not attending school, those

receiving public aid or private support and persons with disabilities).

4.333. Additional reasons for not entering the labour force that are considered particularly

important at national or regional level, such as “engaged in own-use production of goods”

(for example, foodstuﬀs from agriculture, ﬁshing, hunting or gathering) should also be taken

into account in the classiﬁcation of population outside the labour force.

7.4. Characteristics of jobs and establishments

4.334. Once the labour force status of persons has been established, additional important topics

regarding the labour market participation of the population relate to the characteristics of their

jobs and of the establishments in which they work. ese include in particular status in employ

ment, occupation, place of work, industry, institutional sector, working time and income.

4.335. A job is deﬁned as the set of tasks and duties performed or meant to be performed

by one person for a single economic unit. Persons in employment can and do sometimes

have more than one job in the reference period. In such cases the main job is deﬁned in the

international standards as that with the longest hours usually worked even if the employed

person was not at work in the reference period.

152

4.336. Job-related characteristics are generally collected in reference to the main job for

persons in employment, and may also be collected in reference to the last main job (if any)

for persons not in employment (that is, unemployed or outside the labour force). is allows

for classiﬁcation of the labour force (that is, employed persons and unemployed persons) and

of persons outside the labour force by characteristics of their (last) main job. Once the (last)

main job is identiﬁed, it is essential that all subsequent questions refer to that same job, even

if the respondent was not at work in the reference period. e census questionnaire or the

census information taken from registers should be designed in a way that will ensure that

the variables “status in employment”, “occupation”, “industry”, and “institutional sector” are

measured for the same job. is should be a central concern also for countries that rely on the

use of administrative registrations for the capturing of the correct values of these variables.

4.337. e collection of data on characteristics of the last main job of unemployed persons,

especially occupation, industry and status in employment, may be useful in order to inform

policies aimed at promoting employability and job creation. To serve this purpose, it is gener

ally recommended to set a time limit for past employment experience (for example, during

the last ﬁve or ten years) and only collect information on the characteristics of the last main

job if it was held within the time limit.

4.338. When secondary jobs held in the reference period are also identiﬁed, the questionnaire

should be designed so as to enable clear and separate identiﬁcation of characteristics relating

to main and secondary jobs. Identiﬁcation of secondary jobs is particularly important in

countries where multiple job holding is commonplace, particularly in agriculture, and when

collecting information on income from employment and working time, in order to support

analysis of the relationship between employment, income and poverty.

152

Nineteenth International Confer-

ence of Labour Statisticians,

Resolution Concerning Statistics

of Work, Employment and Labour

Underutilization (Geneva, 2013),

para. 12(b).

233Population and housing census topics 233

7.5. Status in employment (core topic)

4.339. Status in employment refers to the type of explicit or implicit contract of employment

with other persons or organizations that the employed person has in his or her job. e basic

criteria used to deﬁne the groups of the classiﬁcation are the type of economic risk, an ele

ment of which is the strength of the attachment between the person and the job, and the

type of authority over establishments and other workers that the person has or will have in

the job. Care should be taken to ensure that an employed person is classiﬁed by status in

employment on the basis of the same job used for classifying the person by “occupation”,

“industry” and “sector”.

4.340. For purposes of international comparison, it is recommended that the main job of

employed persons be classiﬁed by status in employment in accordance with the latest stand

ards for statistics on this topic. At the time the present set of census recommendations was

approved, a revision of these standards was under way and expected to be completed by

2018.

153

e latest standard was the International Classiﬁcation of Status in Employment

(ICSE-93) adopted by the Fifteenth International Conference of Labour Statisticians in

1993.

154

Based on ICSE-93, jobs may be classiﬁed by status in employment as follows:

(a) Employees;

(b) Self-employed:

i. Employers;

ii. Own-account workers;

iii. Members of producers’ cooperatives;

iv. Contributing family workers;

4.341. An employee is a person who works in a job where the explicit or implicit contract of

employment gives the incumbent a basic remuneration that is independent of the revenue

of the unit for which he or she works (this unit can be a corporation, a non-proﬁt institu

tion, a government unit or a household). Employees are typically remunerated by wages and

salaries, but may be paid by commission from sales, or through piece rates, bonuses or in-

kind payment such as food, housing or training. Some or all of the tools, capital equipment,

information systems and premises used by the incumbent may be owned by others, and the

incumbent may work under the direct supervision of or according to strict guidelines set by

the owner or persons in the owner’s employment.

4.342. A self-employed person is one who works in a job where the remuneration is directly

dependent upon the proﬁts (or the potential for proﬁts) derived through market transactions

from the goods and services produced. e term “self-employed” refers to all the subcatego

ries under (b) in paragraph 4.340: employers; own-account workers; members of producers’

cooperatives; and contributing family workers.

4.343. An employer is a person who, working on his or her own account or with one or a few

partners, holds a self-employment job and, in this capacity, has engaged on a continuous basis

(including the reference period) one or more persons to work for him or her as employees.

e incumbent makes the operational decisions aﬀecting the enterprise, or delegates such

decisions while retaining responsibility for the welfare of the enterprise. Some countries may

wish to distinguish among employers according to the number of persons they employ.

4.344. An own-account worker is a person who, working on his or her own account or with

one or a few partners, holds a self-employment job, and has not engaged any employees

on a continuous basis. (Note, however, that during the reference period an own-account

worker may have engaged one or more employees on a short-term and non-continuous basis

without being thereby classiﬁable as an employer.) Persons engaged in agriculture (including

153

Information about the issues that

may be addressed in the revision

of these standards may be found

in Nineteenth International Con-

ference of Labour Statisticians,

“Room Document 8”, Revision of

the International Classiﬁcation of

Status in Employment (ICSE-93)

(Geneva, 2013).

154

For more details see Fifteenth

International Conference of

Labour Statisticians, Resolution

Concerning the International Clas-

siﬁcation of Status in Employment

(Geneva, 1993).

Principles and Recommendations for Population and Housing Censuses, Revision 3234

livestock care), ﬁshing, hunting and gathering, intended mainly for own consumption by

their households, are no longer included in employment on the sole basis of that activity and

should therefore not be considered as “own-account workers”. Instead, participation in these

productive activities is to be measured through the separate concept of “own-use production

of goods” (see paragraphs 4.376-4.381).

4.345. A member of a producers’ cooperative is a person who holds a self-employment job in an

establishment organized as a cooperative, in which each member takes part on an equal footing

with other members in determining the organization of production, sales or other work, invest

ments and the distribution of proceeds among the members. Note that employees of producers’

cooperatives are not to be classiﬁed as in this group but should be classiﬁed as “employees”.

4.346. A contributing family worker is a person who holds a self-employment job in a market-

oriented establishment operated by a related person living in the same or in another house

hold, and who cannot be regarded as a partner (that is to say, an employer or own-account

worker) because the degree of his or her commitment to the operation of the establishment,

in terms of working time or other factors to be determined by national circumstances, is not

at a level comparable with that of the head of the establishment. Where it is customary for

young persons, in particular, to work without pay in a market-oriented enterprise operated

by a related person who does not live in the same household, the requirement that the person

lives in the same household may be relaxed.

4.3 47. Persons not classiﬁable by status include those persons with jobs about which insuf

ﬁcient information is available, or who cannot be included in any of the preceding categories

(for example, persons assisting with the tasks or duties of an employee job held by a family

member living in the same or in another household).

4.348. When members of the armed forces paid in cash or in kind are counted among the

employed, they should be included in the category of employees. However, because of the

wide range of national practices in the treatment of the armed forces, it is recommended that

census tabulations and related notes provide an explicit indication of the status in employ

ment category in which they are included.

4.349. ere are several groups of workers that are on the margin between employee and

self-employed, such as owner-managers of incorporated enterprises (see following paragraph),

outworkers, contract workers and commission workers.

155

Consultations between national

accountants and labour market analysts will be necessary to make decisions about the treat

ment of these groups in a consistent manner, and depending on the descriptive and analytical

purposes of the statistics.

4.350. Owner-managers of incorporated enterprises are workers who hold a job in an incorpo

rated enterprise in which they (a) alone, or together with other members of their families or

one or a few partners, hold controlling ownership of the enterprise; and (b) have the authority

to act on its behalf as regards contracts with other organizations and the hiring and dismissal

of employees, subject only to national legislation regulating such matters and the rules estab

lished by the board of the enterprise.

4.351. In most census questionnaires, the information concerning status in employment will

be captured through precoded alternatives where only a few words can be used to convey the

intended meaning of each category. is may mean that classiﬁcation of some of the situa

tions on the borderline between two or more categories will be carried out according to the

subjective understanding of the respondent rather than according to the intended distinc

tions. is should be kept in mind in designing the questionnaire and also when presenting

the resulting statistics. Countries that rely on the direct use of administrative records for the

classiﬁcation of persons according to status in employment may ﬁnd that the group “contrib

uting family workers” cannot be separately identiﬁed. ose who would have been classiﬁed

155

For a discussion of the treatment

of these groups, see Fifteenth

International Conference of

Labour Statisticians, Resolution

Concerning the International Clas-

siﬁcation of Status in Employment

(Geneva, 1993); and Nineteenth

International Conference of

Labour Statisticians, “Room

Document8”, Revision of the

International Classiﬁcation of

Status in Employment (ICSE-93)

(Geneva, 2013).

235Population and housing census topics 235

as being in this group when using a questionnaire may either be classiﬁed as part of one of

the other groups or excluded from persons in employment.

7.6. Occupation (core topic)

4.352. Occupation refers to the type of work done in a job by the person employed (or the type

of work done in the last job held, if the person is unemployed), irrespective of the industry

or the status in employment in which the person’s job should be classiﬁed. Type of work is

considered in terms of the main tasks and duties performed in the job.

4.353. For purposes of international comparison, it is recommended that countries make it

possible to prepare tabulations involving occupations in accordance with the latest revision

available of the International Standard Classiﬁcation of Occupations (ISCO). At the time the

present set of census recommendations was approved, the latest revision was the one adopted

by a Tripartite Meeting of Experts in Labour Statistics in 2007 and endorsed by the Gov

erning Body of the International Labour Organization in 2008

156

and generally known as

ISCO-08. Countries coding occupation according to a national standard classiﬁcation should

establish a correspondence with ISCO either through double coding or through mapping

from the detailed groups of the national classiﬁcation to ISCO.

4.354. Countries should code the collected occupational responses at the lowest possible

level of ISCO or a related national classiﬁcation supported by the information given in each

response. In order to facilitate detailed and accurate coding, it would be useful for the census

questionnaire to ask each employed person for both the occupational title and a brief descrip

tion of the main tasks and duties performed on the job. Information provided in response

to the industry questions (see following section) may also be used to assist in the coding of

occupation data, where the occupation response on its own is insuﬃcient to assign a detailed

occupation classiﬁcation code.

4.355. In preparation for the coding of the occupation responses, the organization respon

sible for the census should prepare a coding index reﬂecting the type of responses that will

be given by the respondents. e coding index should be constructed by occupational clas

siﬁcation experts on the basis of responses to similar questions in other data collections,

such as previous censuses, census tests and labour force surveys, as well as input from job

placement oﬃcers of the employment service and the content of newspaper advertisements

of vacant jobs. e coding index should clearly distinguish between responses belonging to

“not elsewhere classiﬁed” categories and responses that do not provide enough information

to determine an occupational group.

7.7. Industry (core topic)

4.356. Industry (branch of economic activity) refers to the kind of production or activity of

the establishment or similar unit in which the job(s) of the employed or unemployed person

was located during the time reference period established for data collection on economic

characteristics.

157

4.357. For purposes of international comparison, it is recommended that countries compile

information on industry according to the most recent revision of the International Standard

Industrial Classiﬁcation of All Economic Activities (ISIC) available at the time of the census.

At the time this present set of census recommendations was approved, the fourth edition of

ISIC, adopted by the United Nations Statistical Commission at its thirty-seventh session in

2006, was the latest revision available. Countries coding industry according to a national

standard classiﬁcation should establish correspondence with ISIC either through double cod

ing or through mapping from the detailed groups of the national classiﬁcation to ISIC.

156

“Structure”, “Group Deﬁnitions”

and “Correspondence Tables”,

International Standard Classiﬁca-

tion of Occupations (ISCO-08),

vol.1 (Geneva, International

Labour Oﬃce, 2012).

157

For those persons who are

recruited and employed by one

enterprise but who actually work

at the place of another enterprise

(called agency workers or second-

ed workers in some countries),

there would be user interest in

gathering information about the

industry of the employer as well

as the industry of the place of

work. However, the collection of

both would be more appropriate

in a labour force survey rather

than in a population census. The

industry of the actual place of

work may provide more reliable

reporting of the “industry” vari-

able in a population census. Any

such choice should, however, be

consistent with the treatment

of this group in the System of

National Accounts.

Principles and Recommendations for Population and Housing Censuses, Revision 3236

4.358. Countries should code the collected industry responses at the lowest possible level of

ISIC or a related national classiﬁcation supported by the information given in each response. In

order to facilitate detailed and accurate coding, for each job to be coded, the census question

naire should ask for the main products and services produced or the main functions carried

out at the establishment or enterprise in which the person was employed. It is recommended

that the name and address of the establishment should also be collected (see also paragraph

4.363). Countries with business registers that are complete and up to date can then use this

response as a link to the register in order to obtain the industry code given to the establishment.

4.359. In preparation for the coding of the industry responses that cannot be matched to a

precoded register, the organization responsible for the census should create a coding index

that reﬂects the type of responses that will be given on the census questionnaire. is coding

index should be constructed by industry classiﬁcation experts on the basis of available lists

of enterprises, establishments, businesses and so forth, as well as from responses to similar

questions in other data collections, including previous censuses, census tests and labour force

surveys. e coding index should clearly distinguish between responses belonging to “not

elsewhere classiﬁed” categories and responses that do not provide enough information to

allow for the coding of a detailed industry group.

7.8. Place of work

4.360. Two main topics related to the place of work of persons in employment are the type of

workplace and its geographic location. e type of workplace refers to the nature of the place

where the person performed his or her main job and distinguishes between the home and

other workplaces, whether ﬁxed or otherwise.

4.361. ree main categories, or a variation thereof necessitated by national circumstances,

are recommended for classifying the type of workplace:

(a) Work at home. is category includes those who perform the tasks and duties

of their main job from within the home, such as farmers who work and live on

their farms, homeworkers, self-employed persons operating (work)shops or oﬃces

inside their own homes, and persons working and living at work camps.

(b) No ﬁxed place of work. is category should be restricted to persons who, in per

forming the tasks and duties of their main job, travel in diﬀerent areas and who

do not report daily in person to a ﬁxed address as a work base, for example, travel

ling salespersons, long-distance commercial vehicle drivers, seafarers, ﬁshers and

own-account taxi drivers. It also includes ambulant vendors, operators of street

or market stalls that are removed at the end of the workday, construction workers

working at diﬀerent sites during the reference period and push-cart operators.

should be included in this category, including persons who move around in their

job but have a ﬁxed-base location to which they report daily, such as bus and taxi

drivers (with a base), train and airline staﬀ, and operators of street and market

stalls that are not removed at the end of each workday. is group may also

include individuals who travel to work, on a regular basis, across the national

border to a neighbouring country.

4.362. It is likely that for some jobs, performance is at more than one location (for example, at

home some of the time or season and in a ﬁxed location outside the home at other times) or the

category cannot be clearly distinguished. One approach, in the case of the former, would be to

select the place where the individual spends or spent a major part of his or her working time.

Where the distinction between categories is blurred, as is the case for work done, for example,

on a rented plot of land adjacent to one’s home, it would be useful to identify borderline cases,

237Population and housing census topics 237

according to national circumstances. Speciﬁc instructions should be given to the enumerators

on how to select between two or three possible responses to classify borderline cases.

4.363. e geographic location of the place of work can provide useful information for plan

ning when used together with information on place of residence. To this end, countries may

collect, for employed persons with a ﬁxed place of work outside the home, information on

the location of the place of work (or the reporting place) during the reference period. e

information collected should relate to the smallest civil division in which the job is performed,

for example, in order to establish commuter ﬂows from the place of residence to the place

of work. Some countries investigating this topic in the population census have recorded the

actual address of the place of work, allowing detailed tabulations and mapping of place of

residence by geographic location of place of work. Information on actual address of the place

of work can also be useful for industry coding (see paragraph 4.358) in countries where a busi

ness register has been developed that shows the industry code of each recorded establishment.

4.364. In some countries there may be concerns about the sensitivity of questions on the

address of place of work owing to fears that there may be follow-up to a respondent’s employer.

In many developing countries, it may not be possible to gather information on actual address

of place of work because street addresses do not exist, and for proxy responses, the address

may not be known. In those situations, it would be useful to consider collecting information

on the village, suburb, or similar low level of geography.

4.365. Additional questions may also be asked on the method of travel to work in order to

produce statistics on travel-to-work patterns, valuable as basis for transportation planning.

7.9. Institutional sector of employment

4.366. e institutional sector of employment relates to the legal organization and principal

functions, behaviour and objectives of the enterprise with which a job is associated.

4.3 67. Following the deﬁnitions provided in the System of National Accounts, distinction

should be made between the following institutional sectors:

(a) Corporation, comprising non-ﬁnancial and ﬁnancial corporations (in other words

incorporated enterprises, private and public companies, joint stock companies,

limited liability companies, registered cooperatives, limited liability partnerships,

and so forth) and quasi-corporations (that is to say, an unincorporated enterprise

that is managed as if it were a corporation, in that a complete set of accounts is

kept), as well as non-proﬁt institutions, such as hospitals, schools and colleges that

charge fees to cover their current production costs;

(b) General government, comprising central, state and local government units together

with social security funds imposed or controlled by those units, and non-proﬁt

institutions engaged in non-market production controlled and ﬁnanced by gov

ernment, or by social security funds;

societies, sports and cultural clubs, charitable institutions and aid agencies) that

provide non-market goods and services for households (that is to say, free or at

prices that are not economically signiﬁcant) and whose main resources are from

voluntary contributions;

(d) Households (including unincorporated enterprises owned by households) com

prising unincorporated enterprises directly owned and controlled by members

of private and institutional households (made up of persons staying in hospitals,

retirement homes, convents, prisons and so forth, for long periods of time), either

individually or in partnership with others. Partners may be members of the same

household or from diﬀerent households.

Principles and Recommendations for Population and Housing Censuses, Revision 3238

4.368. In most census questionnaires, the information concerning institutional sector of

employment will be captured through precoded alternatives where only a few words can be

used to convey the intended meaning of each category. is may mean that classiﬁcation of

some units on the borderline between two or more categories will be carried out according to

the subjective understanding of the respondent rather than according to the intended distinc

tions. is should be kept in mind when presenting the resulting statistics.

7.10. Working time

4.369. e number of employed persons provides only a very rough estimate of the volume of

work performed, especially when such persons have non-standard working hours. Inclusion

in the census of an item on time worked helps to ensure a more accurate measurement of the

concept by capturing the full contribution of persons who were in and out of the workforce

or who worked only for a brief time during the year.

4.370. To provide a comprehensive measure of working time in employment that will best

inform policy and analytical needs, it may be preferable to collect information about the total

hours worked in all jobs rather than to limit the information to hours worked in the main job.

4.371. Information on two distinct concepts of working time can be collected in a popula

tion census: hours actually worked and hours usually worked.

4.372. Hours actually worked is deﬁned as the time spent in a job for the performance of

activities that contribute to the production of goods and/or services during a speciﬁed refer

ence period. It covers the time spent in “direct hours”, in “related hours”, “down time” and

short “resting time”. “Direct hours” is the time spent carrying out the tasks and duties of the

job—and may be performed in any location. “Related hours”, while not leading directly to

goods produced or services provided, is the time spent maintaining, facilitating or enhancing

productive activities, including upkeep of the workplace, changing time or decontamina

tion of work clothes, purchasing or transporting materials, waiting for business, customers

or patients, on-call duties, travelling between work locations, and work training or skills

enhancement required by the economic unit. In practice, “down time” includes unavoidable,

temporary interruptions to work (for example machinery or Internet breakdown, lack of sup

plies). “Resting time” is inactive time for short rest or refreshment in the course of performing

job-related activities, (for example coﬀee breaks). Longer breaks for meals, time spent not

working because of vacation, holidays, sickness, industrial disputes, etc., commuting to work

(if not also performing job tasks or duties) and educational leave even if paid, are excluded

from hours actually worked.

4.373. Measurement of hours actually worked in employment, in the context of the popula

tion census, is usually collected using one direct question; it is optimally measured using a set

of questions, requesting hours separately for each day of the week. For employed persons not

at work in the short reference period, it is possible to have a value for hours actually worked

of zero (for persons away on leave) or reduced (if a part of the reference period was taken oﬀ

for sickness, holiday, or other purpose).

4.374. Hours usually worked is deﬁned as the typical value of the hours actually worked in a

job per short reference period (for example one week) over a long observation period (month,

quarter, season, year) that comprises the short reference period itself. is “typical value” of

time worked during a normal or typical week may be the modal number of the hours actually

worked in the short period as distributed over the long period. is would include overtime

hours regularly worked whether paid or unpaid. Days and hours not usually worked and

unusual periods of overtime are not included.

4.375. Measurement of hours usually worked in employment relating to the short reference

period of one week can be done with one direct question: how many hours do you usually

239Population and housing census topics 239

work per week (in your main job or in all jobs)? For persons with more than one job dur-

ing the reference week, to record both working time in the main job (for which the other

descriptive variables are collected) and total working time (sum of working time in all jobs)

the questionnaire would require at minimum two questions.

7.11. Participation in own use production of goods (core topic)

4.376. Countries where production of goods for own ﬁnal use (such as foodstuﬀs from

agriculture, ﬁshing, hunting and gathering, water, ﬁrewood and other household goods)

represents an important component of the livelihood of a part of the population, whether as

a main or secondary activity, will need to consider collecting information in the population

census on the number of persons engaged in this form of work (previously included within the

concept of employment). Such information is essential for benchmarking purposes, especially

where household surveys are not frequent, for comprehensive sectoral analysis, particularly of

work in agriculture, forestry and ﬁshing, and to enable integration of the population census

with the agricultural census (see also paragraphs 4.387-4.396).

4.377. Persons in own-use production of goods are all those above the speciﬁed age who, during

a speciﬁed reference period, performed “any activity” to produce goods for own ﬁnal use.

e notion “for own ﬁnal use” is interpreted as production where the intended destination

of the output is mainly for ﬁnal use by the producer in the form of capital formation, or ﬁnal

consumption by household members, or by family members living in other households.

4.378. According to international standards, “any activity” to produce goods (within the

2008 System of National Accounts production boundary) covers work performed for at least

one hour in the following activities, when the intended destination of the output is mainly

for own ﬁnal use, as speciﬁed above:

(a) Producing and/or processing for storage agricultural, ﬁshing, hunting and gather

ing products;

(b) Collecting and/or processing for storage mining and forestry products, including

ﬁrewood and other fuels;

(d) Manufacturing household goods (such as furniture, textiles, clothing, footwear,

pottery or other durables, including boats and canoes);

(e) Building, or eﬀecting major repairs to, one’s own dwelling, farm buildings, etc.

4.379. For measurement purposes, the intended destination of the output is established in

reference to the speciﬁc goods produced, based on self-declaration (that is, mainly for own

ﬁnal use). In the case of goods from agriculture, ﬁshing, hunting or gathering intended

mainly for own consumption, a part or surplus may nevertheless be sold or bartered.

4.380. Persons may engage in own-use production of goods as a main or secondary activity,

throughout the year or on a seasonal basis. To ensure complete coverage, the census questions

on participation in own-use production of goods should be applied to all persons above the

speciﬁed age for collecting information on the economic characteristics of the population,

irrespective of their labour force status. e reference period may refer to the last 12 months,

calendar year, agricultural year or season, as relevant to national circumstances. Where per

tinent, the choice of reference period should promote coherence with the agricultural census

(see also paragraphs 1.44-1.50).

4.381. For assessments of the volume of work performed by persons in own-use production

of goods, particularly when using a long reference period, it may be useful to include a ques

tion on working time, in particular hours usually worked (see paragraph 4.374), or based on

broad categories such as part time or full time, part year or full year, number of months, as

feasible and relevant to the main uses of the statistics.

Principles and Recommendations for Population and Housing Censuses, Revision 3240

7.12. Income

4.382. Countries may wish to collect information on the amounts of income received by

individual persons or households during a speciﬁed reference period, from any source. If this

topic is included in the census, it is recommended that data be obtained for all persons above

a speciﬁed age, whether they are employed or not. Income may be measured at the household

level, or for each individual in the household.

4.383. Income may be deﬁned as all receipts whether monetary or in kind (goods and ser

vices) that are received by the household or by individual members of the household at annual

or more frequent intervals, but excluding windfall gains and other such irregular and typically

one-time receipts. Household income covers (a) income from employment (both paid and

self-employment); (b) income from the production of goods for own ﬁnal use; (c) income from

the provision of household services for own ﬁnal use; (d) property income; and (e) current

transfers received.

158

4.384. e collection of reliable data on income, especially income from self-employment

and property income, is extremely diﬃcult in general ﬁeld enquiries, particularly population

censuses. e inclusion of non-cash income further compounds the diﬃculties. Collection of

household income data in a census, even when conﬁned to cash income, presents special prob

lems in terms of burden of work, response errors, and so forth. erefore, this topic is generally

considered more suitable in a sample survey of households or from administrative data sources

such as tax or social security records. Depending on the national requirements, countries may

nonetheless wish to obtain limited information on personal or household income, by covering

only some of the income components (such as income from employment), for shorter reference

period (such as one month), and cover only cash income. As thus deﬁned, the information

collected can provide some input into statistics that have many important uses.

4.385. According to international standards on the subject, the income from employment

of employed persons should include wages and salaries of employees, income of members

from producers’ cooperatives and the mixed income of employers and own-account workers

operating business and unincorporated enterprises. In addition to the income from employ

ment of employed household members, the total income of the household should include,

for example, the interest, dividends, rent, social security beneﬁts, pensions and life insurance

annuity beneﬁts of all its members. e Handbook on household income statistics

159

provides

further guidance on concepts and methods related to this topic.

4.386. e concepts involved in determining income are not simple to grasp and respondents

may be unable or unwilling to provide exact information. For example, income should include

social security beneﬁts, pension fund contributions and direct taxes withheld from employees’

salaries, but some persons will undoubtedly not include these amounts in reporting their sala

ries. Signiﬁcant items of total household income may also be excluded or misstated. Despite

instructions given to enumerators, the data collected can therefore only be expected to be

approximate. Accordingly, in the presentation of results it is usually appropriate to use broad

income or earnings size classes. As an aid to the interpretation of the results, tabulations of the

data should be accompanied by a description of the items of income assumed to be included

and, if possible, an estimate of the accuracy of the ﬁgures.

8. Agriculture

8.1. Introduction

4.387. In this section two non-core topics on agriculture are presented. ese two alterna

tive topics could be considered by countries that would like to collect information in their

158

Seventeenth International Con-

ference of Labour Statisticians,

Resolution Concerning Household

Income and Expenditure Statistics

(Geneva, 2003), paras. 4-5, avail-

able from www.ilo.org/wcmsp5

/groups/public/---dgreports

/---stat/documents/normativein

strument/wcms_087503.pdf.

159

Canberra Group Handbook on

Household Income Statistics,

2nd ed. (2011), available from

www.unece.org/ﬁleadmin/DAM

/stats/groups/cgh/Canbera

_Handbook_2011_WEB.pdf.

241Population and housing census topics 241

population census that would facilitate the preparation of the frame of agricultural holdings

in the household sector, for a subsequent agricultural census (see also paragraph 1.44-1.50).

4.388. With the ﬁrst topic, at the household level, information is collected on whether any

member of the household is engaged in own-account agricultural production activities at their

place of usual residence or elsewhere. is information can be restricted to limited key items

or may include a more comprehensive agricultural module. With the second topic, at the

individual person level, information is collected to identify persons involved in agricultural

activities during a long reference period such as a year before the census, in contrast to most

of the topics included in a population census for which the information generally relates to

the shorter reference period of a week before the census.

8.2. Own-account agriculture production

4.389. Some countries may want to use the population census to identify households engaged

in own-account agricultural production. is information is useful for agriculture-related analy

sis of the population census and for use as a frame for a subsequent agricultural census or other

surveys. In this case, information should be collected for all households on whether any member

of the household is engaged in any form of own-account agricultural production activities.

4.390. Where possible, information should be collected to identify whether the household is

engaged in any form of own-account agricultural production, covering the main agricultural

activities important to the country (which can include crops, livestock and related activities).

Information may also be collected on forestry, ﬁshery and aquaculture activities in case they

are important for a country. Additional information should also be collected giving a measure

of farm size—such as the area or number of plots used for agricultural purposes. Countries

wishing to collect more comprehensive agricultural data may wish to include an agriculture

module with the core data items recommended by the FAO World Programme for the Census

of Agriculture 2020 (WCA 2020) and the FAO/UNFPA Guidelines for Linking Population and

Housing Censuses with Agricultural Censuses (FAO and UNFPA, 2012).

4.391. Where aquacultural production is important at the household level, information can

also be collected on whether or not any member of the household is engaged in any form of

own-account aquacultural production activities.

4.392. Agricultural production activities refer to groups 011, 012, 013, 014 and 015 of ISIC

(Rev. 4.0), namely:

Group 011: Growing of non-perennial crops

Group 012: Growing of perennial crops

Group 013: Plant propagation

Group 014: Animal production

Group 015: Mixed farming.

Aquacultural production activities refer to group 032 of ISIC (Rev. 4.0), namely:

Group 032: Aquaculture

8.3. Characteristics of all agricultural activities during the last year

4.393. e population census normally collects information about a person’s main job or

work activity during a short reference period, which may not cover all persons working in

agriculture because of the seasonality of many agricultural activities and because agriculture

may not be the main activity of the person. To overcome this problem, information should

be collected on all persons that carried out agricultural activities during the year preceding

the population census day. e information to be collected should include the occupation

and status of employment of all agricultural jobs, and could be expanded to cover working

Principles and Recommendations for Population and Housing Censuses, Revision 3242

time and whether the job was performed as a main or secondary activity. Given the newly

adopted conceptual framework for work statistics, information should also be collected on

participation in own-use production of agricultural goods, particularly in countries where

subsistence agriculture is practised by part of the population (see paragraphs 4.376-4.381).

4.394. Information on occupation and status in employment of all agricultural jobs (main

and secondary), and on participation in own-use production of agricultural goods, can be

used as an alternative way to facilitate identiﬁcation of households engaged in own-account

agricultural production activities (see paragraphs 4.389-4.392). Status in employment and

participation in own-use production of agricultural goods could be used to distinguish

between households that are engaged in own-account agricultural production activities and

households with members engaged in agricultural activities only as paid employees, which

would not qualify them as households with own-account agricultural production.

4.395. Where aquacultural production is important in a country, similar information on

occupation and status in employment of all aquacultural jobs, and on participation in own-

use production of aquacultural goods, during the year preceding the population census day

can also be included. e information to be collected could be expanded, as required, to

include working time and whether the job was performed as a main or secondary activity.

4.396. An agricultural job or work activity is deﬁned as a job or work activity in the agricul

tural industry as deﬁned by groups 011, 012, 013, 014 and 015 of ISIC (Rev. 4.0); namely:

Group 011: Growing of non-perennial crops

Group 012: Growing of perennial crops

Group 013: Plant propagation

Group 014: Animal production

Group 015: Mixed farming.

An aquacultural job or work activity is deﬁned as a job or work activity in the aqua-

cultural industry as deﬁned by group 032: Aquaculture of ISIC (Rev. 4.0).

II. Housing census topics

A. Factors determining the selection of topics

4.397. In line with the overall approach to revision 3 of Principles and Recommendations for

Population and Housing Censuses, the selection of housing census topics, as with the popula

tion topics described in chapter I, is based on the outputs expected to be produced. erefore,

the ﬁrst step involves the clear identiﬁcation of expected outputs; the core and additional

topics are then decided on that basis. It is recommended that countries collect data on the

core topics and also produce the recommended tabulations, as this would improve the inter

national harmonization and comparability of statistics through the use of common concepts,

deﬁnitions and classiﬁcations. Use of an agreed-upon international approach would also

enhance the capacity of countries to generate statistics for monitoring the socioeconomic

situation of their populations, including for the provision of data for the internationally

agreed-upon development goals.

4.398. Also with reference to the selection of topics to be included in a housing census, limit

ing statistical enquiries to the collection of data that can be processed and published within a

reasonable period of time was deemed important. Such cautions are especially applicable to a

housing census, since it is customary to conduct housing and population censuses as simulta

neous or consecutive operations. ere is a high probability that the number of data required

243Population and housing census topics 243

from a census may be beyond the capacity of enumerators to collect or census agencies to

process. It may be suﬃcient in some developing countries, for example, to ascertain only the

number of housing units and other sets of living quarters of various types, the number and

characteristics of the occupants thereof and the availability of a water supply system.

4.399. In this context, countries should not attempt to collect housing data that are so incom

plete that they fail to serve the principal purposes for which they are required. It is important,

therefore, for census takers to consult closely with the principal users at an early planning

stage in order to identify the data that are of highest priority and the means of supplying

them in the most useful formats.

4.400. e topics, therefore, to be covered in a housing census (that is to say, the subjects

regarding which information is to be collected for living quarters, households and buildings)

should be based on a balanced consideration of:

(a) e needs of the broad range of data users in the country at both the national

and local area level (national priority);

(b) e achievement of the maximum degree of international comparability, both

within regions and on a worldwide basis (international comparability);

ability of the public to give accurate information on the topics (suitability);

(d) e technical competence of the enumerators in regard to obtaining information

on the topics (suitability);

(e) e total national resources available for conducting the census (resources);

(f ) e availability of relevant information held in alternative data sources (alterna

tive sources).

4.401. Such a balanced consideration will need to take into account the advantages and

limitations of alternative methods of obtaining data on a given topic within the context of an

integrated national programme for gathering housing statistics.

4.402. In selecting housing topics, regard should be given to the usefulness of historical

continuity, which provides the opportunity for measuring changes over time. Census takers

should avoid, however, collecting information that is no longer required. Information should

not be collected simply because it was collected in the past. It becomes necessary, therefore,

to review periodically the value of even long-standing topics and to re-evaluate the need for

their continued collection.

4.403. In selecting the housing topics, regard should also be given to the usefulness of histori

cal continuity, which provides the opportunity for comparison of changes over a period of

time. Census takers should avoid, however, collecting information that is no longer required

by users. Information should not be collected simply because it was traditionally collected in

the past, bearing in mind changes in the socioeconomic and housing circumstances of the

country. It becomes necessary, therefore, in consultation with a broad range of users of cen

sus data, to review periodically the value of even long-standing topics and to re-evaluate the

need for their continued collection, particularly in the light of new data needs and alternative

data sources that may have become available for investigating topics hitherto covered in the

population and housing census. Each of ﬁve key factors that need to be taken into account in

reaching a ﬁnal decision on census content are brieﬂy reviewed in the following paragraphs.

Principles and Recommendations for Population and Housing Censuses, Revision 3244

1. National priority

4.404. e priority of designing a housing census should be to meet national needs. Should

there be any conﬂict between such national needs and regional or global recommendations,

national needs should take precedence, followed by regional recommendations and ﬁnally by

global recommendations. e prime consideration is that the census should provide informa

tion on those topics that are of greatest value to the country, with questions framed so as to

elicit data of maximum utility.

4.405. Each country’s decision with regard to the topics to be covered should depend upon