CBS had gained access to those registers thanks to the new Act governing the Central Bureau of Statistics and the Central Commission for Statistics (1996), albeit under strict conditions. The resulting System of Social Statistical Datasets (SSB) became the source for all censuses published from 2001 onwards.
Access to all registers
The 2001 virtual census was conducted using data from these registers combined with sample survey data. By far most of the data came from the municipal population registers on 1 January 2001. Supplementary data were drawn from the SSB (employees and self-employed, commuter journeys), labour force survey (occupation and education level), housing register and housing demand survey (housing data), employment and wages survey, and jobs dataset.
Forty tables were published, 28 with national data and 12 with regional data at COROP (NUTS 3) and municipal level. Thirty of these tables contained population, education, occupation and industry data. Eight tables covered housing and two covered commuting from home to work and vice versa.
Homeless persons also included
CBS was able to cover nearly all groups in the country, even the homeless – the classic example of a forgotten group. Many homeless people are also recorded in registers: lists of people staying in day and in night shelters (source: Federatie Opvang), homeless substance abusers in the National Alcohol and Drugs Information System, and persons with no fixed address according to a decree under the Work and Social Assistance Act (WWB). Naturally, these data were all collected in compliance with official data protection regulations.
Loss of detail
The virtual census cannot replace a real traditional census. Data from traditional censuses, provide extra options to examine and analyse cross links at micro and macro-level, for example in terms of income and education level of members of the same household. These analyses are not possible with virtual census data.
As data protection regulations have also become increasingly stringent, stricter statistical disclosure control and data security demands apply to the statistical production process. Table cells comprising too few persons, for example, are repressed, or the data are rounded, again resulting in loss of information. One consequence of this is that the results of recent censuses are no longer as detailed as results from traditional censuses.