The 2001 Census is a virtual census, which means that it is composed of available register data and existing surveys. This results however in not having all variables available for all individual records. As a consequence the complete set of micro data is not released, but an anomynised balanced sample of the individual personal records for which all demographic and economic variables are available. Variables: Sex, age, household position, household size, place of residence one year prior to the census, country of citizenship, country of birth, level of educational attainment, economic status, occupation, branch of current economic activity, marital status. For detailed information see also Statistics Netherlands website