1. The Dutch Virtual Census based on registers and already existing surveys Eric Schulte Nordholt Senior researcher and project leader of the Census Statistics Netherlands Division Social and Spatial Statistics Department Support and Development Section Research and Development e.schultenordholt@cbs.nl Workshop on censuses using registers in Geneva (21 May 2012)

2. 2 Contents History of the Dutch Census Introduction Virtual Census Data sources Combining sources: micro linkage Combining sources: micro integration Conditions facilitating use of administrative sources Comparison with other countries Comparison with other years Microdata availability Preparing the 2011 Census Conclusions

3. 3 History of the Dutch Census TRADITIONAL CENSUS Ministry of Home Affairs: 1829, 1839, 1849, 1859, 1869, 1879 and 1889 Statistics Netherlands: 1899, 1909, 1920, 1930, 1947, 1960 and 1971 Unwillingness (nonresponse) and reduction expenses  no more Traditional Censuses ALTERNATIVE: VIRTUAL CENSUS 1981 and 1991: Population Register and surveys development 90’s: more registers → 2001: integrated set of registers and surveys, SSD

4. 4 Introduction Virtual Census Why a Census? Statistical information for research and policy purposes What kind of information? Size of (sub)population(s) Demographic and socio-economic characteristics, at national and regional level Gentlemen’s agreement / Census act Eurostat: coordinator of EU, accession and EFTA countries in the European Census Rounds Census Table Programme, every 10 years

5. 5 Data sources Registers: Population Register (PR) → illegal people excluded, homeless counted at last known address Jobs file, containing all employees Self-employed file, containing all self-employed Fiscal administration Social Security administrations Pensions and life insurance benefits Housing registers Surveys: Survey on Employment and Earnings (SEE) stopped Labour Force Survey data around Census Day Housing surveys

6. 6 Combining sources: micro linkage Linkage key: Registers Citizen Service Number, unique Surveys Sex, date of birth, address (postal code and house number) Linkage key replaced by RIN-person Linkage strategy Optimizing number of matches Minimizing number of mismatches and missed matches

7. 7 Combining sources: micro integration Collecting data from several sources  more comprehensive and coherent information on aspects of a person’s life Compare sources - coverage - conflicting information (reliability of sources) Integration rules - checks - adjustments - imputations Optimal use of information  quality improves Example: job period vs. benefit period

8. 8 Conditions facilitating use of administrative sources Legal base (Statistics Act) Public approval (‘Big Brother is watching you’) Cooperation among authorities (mainly government organisations) Comprehensive and reliable register system (administrative versus statistical quality) Unified identification system (preferably unique ID-numbers)

9. 9 Comparison with other countries Traditional Census (complete enumeration): Most countries in the world (including the UK and the US) Traditional Census (partial enumeration) and Registers: Some countries (e.g. Germany, Poland and Switzerland) Rolling Census: France Fully or largely register-based (Virtual) Census: Four Nordic countries (Norway, Sweden, Finland and Denmark), the Netherlands, Austria and Slovenia

10. 10 Comparison with other years

11. 11 Microdata availability One percent samples for three years (1960, 1971 and 2001) IPUMS (Integrated Public Use Microdata Series): http://www.ipums.org/international/index.html Weighting to population totals Protecting according to rules for public use files Microdata sets for all three years available for research! DANS (Data Archiving and Networked Services): http://www.dans.knaw.nl/en/

12. 12 Preparing the 2011 Census Sources (the PR as backbone of the census, changes in contents and quality of registers, remaining information from surveys) Estimation method (repeated weighting, new version of the software, fall-back option of weighting to PR, less imputations, zero cells problem) Statistical Disclosure Control of the hypercubes (Workshop on SDC of Census Data in April 2012) Tabular data in SDMX format and the Census Hub

13. 13 Conclusions (1) A Dutch Virtual Census: yes, we can! Micro integration remains important Repeated weighting was a success Advantages: Relatively cheap (small cost per inhabitant) Quick (short production time) Disadvantages: Dependent on register holders (statistics is not their priority), timeliness of registers, concepts and population of registers may differ from what is needed (keep good relations with the register holders!) Publication of small subpopulations sometimes difficult or even impossible because of limited information

14. 14 Conclusions (2) Other aspects: Less attention for the results of a virtual census than for a traditional one Difficult to keep knowledge and software up-to- date (Census is running every ten years) Enormous international interest in virtual censuses A lot of interesting census work in the coming years!

15. 15 Time for questions and discussion