Alternatives in Census Designs

Fourth Taskforce Meeting on Population & Housing Censuses

Cairo, 4-5 September 07

Neda Jafar

ESCWA

jafarn@un.org

Background

Most countries conduct traditional census Headcount at a national level statistical portrait/profile (composition,

distribution & socio-economic correlates) Governments uses: taxation, military

service, planning of schools & hospitals

Concerns

Falling response rates Respondent burden Cost Data quality Desire for more accurate information in

non-census years Lack of timeliness of results Under coverage

Population Census Designs

A. Traditional census

B. Traditional census supplemented by annual household surveys

C. Registered-based census

D. Administrative sources and sample surveys – virtual census

E. Sample surveys – rotating census

A. Traditional census

Used by vast majority of countries especially outside Western Europe

Complete enumeration of population

Periodically (every 5-10 years)

Scope for variation Enumeration:

by interviewers self completion form (enumerators/ via postal service)

Location: Count at location or at usual place of residence

Questions: Number and type of questions asked may vary

extensively Use of short & long form

Australia(population: 19 million)

Every 5 years A drop-off/pick up methods without any use

of the postal service Level of undercount determined by PES In 2001 census included questions on use

of PCs and internet 1st time respondents opt giving permission

for releasing record in 99 years In 2006 traditional census

AustraliaThe Future

Two major changes planned Fill in the census form via internet Use post-back in buildings/apartment

blocks (difficult to obtain a response thru pick-up)

Canada(population: 30 million)

Usual residents, every 5 years A drop-off/post-back methods since 1971 Short form contains 7 questions on basic

demographic information Long form sent 1/5 households on

parents’ birthplace, single-sex couples and detailed language question

Canada

Gross under coverage rates have been steadily increasing reaching 3.3% in 1996

In 2006, 2/3 of forms posted out + comprehensive address register

Possible to use the internet to complete the questionnaire

B. Traditional census supplemented by annual hh surveys

A traditional census carried out 5/10 yrs Traditional short form USA “Re-engineered Pop and Housing

Census Prior census, large-scale annual surveys Complemented by Community Survey

Programme Surveys since 2003 Replace long form

USAAmerican Community Survey

Collection on monthly samples Each sample has 3-month collection cycle Each collection cycle has 3 phases:

Questionnaire mailed Use of computer-assisted interviews to

follow up on non respondents Personal interview to non-respondent

Type Data Sources

Periodicity Advantages Constraints Prerequisites

Traditional census and annual surveys

- traditional census for short form-Sample surveys for long form type of data

-every 10 yrs

- Annually collect long-form data through 10 yrs

- reduce operational complexity of 10 yr census-Complete updated frame-Timely and quick release of data-Enhances professional ism

- high financial commitments for survey component-Estimation procedures complex-adoption of moving averages is troubling users accustomed to data for all geographic areas at one point in time-Needs to be a 3 year and 5 year accumulation of data required for areas with fewer than 65,000 people

-good sample frames-A solid infrastructure with good statistical capacity-Long term financial commitment to survey programme

USAThe Future

2010 census will run on traditional lines No Long form Use adm records data for non response hh ACS with annual sample size of 3m hh 10years ¼ population cover (>long form) Low level/annual pop reliable estimates for

areas/pop >65,000 available 1st yr of the national survey

C. Register-based census

Data from adm. registers combined at micro level

No questionnaires are sent Covers all private hh and dwellings In principal, can replace a census

completely. In practice, constrained by the quality &

extent of data in registers

Type Data Sources

Periodicity Advantages Constraints Prerequisites

Register-based census

Adm registers

Flexible -Reduce cost-periodicity & reference date flexible-No respondent burden-Quick data results

-data limited to registers-maintain & update registers-Complex data merging & cleaning

Availability of comprehensive & relevant registers- Unique personal id #

Italy(population: 57 million)

Every 10 years since to 1861 Municipal population registers, but each

municipality is responsible for its own register and these vary highly in quality

Little incentive to remove people who have died or moved

Italy

Significant difference between resident & registered population

Reasons include: Students registered in one municipality

but live n another People temporary resident in one

municipality due to work People performing military service

Italy

Traditionally census was used to update the registers

Registers are used to estimate undercount in census

In 1991 the raw register figures gave 5% undercount (attempts to remove superfluous register data reduced this figure to 1%)

ItalyThe Future

ISTAT attempt to standardize population registers and other adm sources to conduct register-based censuses in the future

Spain(population: 41 million)

2001 census was the first in the world to allow all residents to complete their forms via internet

The existence of municipal population registers was central to census operation

Spain

Paper questionnaires were pre-printed with information from the registers, to be corrected, if necessary Identity code and password to enable

access to the on-line version However only 0.1% of households

responded

D. Adm. sources & Sample surveys

Some countries obtain census information by compiling data from:

different adm registers, and results of sample surveys

Type Data Sources

Periodicity Advantages Constraints Prerequisites

Registers and sample surveys

-Registers-Adm records-Sample surveys

Flexible -Reduce cost-Availability of timely census info-No respondent burden-Reduce probability of publishing contradictory data

-data limited to registers-maintain & update registers-Complex data merging & cleaning

-Availability of comprehensive & relevant registers-Unique personal id #-A good survey programme and frame to supplement registr-based info

The Netherlands(population: 16 million)

1981 traditional census approach abandoned

Stat Netherlands used adm registers and existing sample surveys

However, data at aggregate level i.e. not possible to integrate them fully with survey data

Legislation allowed administrative records to be used to their full potential for statistical purposes, to reduce costs & respondents burden

The Netherlands

Dutch are expected to register with local authorities.

It contains name, address, and basic demographic data (sex, date of birth, and marital status)

Updated once a year on 1 January

The NetherlandsSSB

In 1996, a Social Statistics Database (SSB) contains information at an individual level

Covers residents during year based on pooled population register created at the end of the year

Population register is the spine Other adm records sources: employee

insurance schemes, social security, water electricity, pension

The NetherlandsSSB

The database enables the statistical office to come up with census related results at any chosen time.

File created in a micro-integration process from diff sources

Transformed and adjusted to conform with concepts and definitions set in the census programme

“Repeated weighting” used to generate numerically consistent table sets for data from different sources

The NetherlandsSSB

Matched using variables: sex, date of birth & address

The matching process aims to match over 90% records with no > than 5 % false matches

No Coverage estimate due to lack of another measure of the population

In 2001 called “Virtual Census” based on combined info from diff sources using personal id codes

Denmark (population: 5.4 million)

Central population register (CPR) based on municipal registers

Change in address is compulsory, with birth and death registration update CPR

Other adm registers linked to CPR by unique personal identifier

A register-based population census took place in 1976 and following the establishment of a register of buildings and dwellings, a register-based population and housing census in 1981

Neither of these included any form of fieldwork

Denmark

Statistics Act obliges public bodies to make available any information required by Statistics Denmark for statistical purposes

Consult Statistics Denmark when developing registers to ensure that they are appropriately organized for statistical use

Population statistics are produced every year from the CPR and other administrative sources

Population registers associated with the issuing of identity cards are held at municipality level

E. Sample Surveys

Large-scale continuous annual surveys or rolling survey

Cover whole country over a period of time rather than on one particular day

Cover a region in its entirety or by taking a sample from every area

Merits Cost effective Builds national capacity of NSS Quality of data on annual basis Generate new up-to-date stat info for users Annual estimates from very large sample Annual time series for various adm domains

Type Data Sources

Periodicity Advantages Constraints Prerequisites

sample surveys based census

-Sample surveys

Annual -Data availability annually-Develop & update frames for other specialized surveys-Enhances professional ism

- does not cover all individuals in a particular locality-Exclusion of new buildings in the frame a possibility-Estimate procedures of linking five-year data challenging-response rates may decrease, in >10,000-Small areas results may not be reliable

-good sample frames-A solid infrastructure with good statistical capacity

France

France terms it a “rotating census” Annual collection of data, during a five-year period Based on sample surveys providing pop data for the

adm districts and annual socio-demographic statistics Adopted for 4 main reasons:

No pop registers Several large-scale surveys with results that can

be inferred at relatively low domains While adm data may be available, the files can not

be linked coz there are no personal id number system

Until 1999 no legal obligation to carry out a census and no clear legal framework for conducting traditional census

Rotating Census – New model

Cover every household over a given period of time (5-10 years)

Proportion of population would not be counted at all in 5 years cycle

Census population <10,000 in communes enumerated once every 5 years

Larger communes a sample survey with 40% population will be enumerated i.e. any given commune will be sampled every year

Sampling frame drawn from building register Building register was created initially from 1999

census Updated continually from construction & demolition

permits also other sources & surveys

Conclusions

Only within Western Europe that a complete enumeration is not always attempted

The Scandinavian countries having good population registers or are about to be, the sole means of enumerating population

The Netherlands has a unique model that makes good use of all the sources available-population registers, other administrative sources and sample surveys

Conclusions

France use a rolling model which is part census and part sample survey, and it depends on at least one good administrative sources (building registers)

Italy is looking to develop a more standardized system that can be used to conduct register-based censuses

USA is moving to ‘head count’ plus ‘survey’ model. USA does not have a compulsory population register

Conclusions

1. No two countries are exactly alike even for those that still conduct a traditional census

2. Not every model would work for every country3. Factors depends on

population size, quality of administrative records, population base issues, public perception, political climate, funding, legislative and constitutional issues existence of a reliable population register

Towards a census information-system The ideal situation is not to one approach Optimize use of available sources To avoid faults and to take advantage of the

merits of each. Shift from a census system to a census

information-system where the data are:- Rich - Detailed

- Dynamic - Continuously updated

- Monitors flows ofsequent stock of snapshots