UK Census Data

Decennial population censuses are based around the delivery and collection of a questionnaire to every household in the UK comprising a set of household questions and further questions about each individual member of the household. The answers to these questions form the basis of an extensive range of census output datasets.

UK Census datasets are published by the three national census organizations, the Office for National Statistics (ONS) in England and Wales, the General Register Office Scotland (GROS) and the Northern Ireland Statistics and Research Agency (NISRA). Users of 1991 and earlier censuses will find reference to the Office for Population Censuses and Surveys (OPCS), which was the predecessor of ONS. Strictly, there is not a single UK census but parallel independent censuses conducted by the different organizations on a decennial basis in years ending with 1 (i.e. 1991, 2001, etc.)

• Census data aggregated for geographical areas are the most widely-used census outputs and very many cross-tabulations of the census questions are available. These datasets have been known by different names in successive censuses.
• In addition to the area-based data, digital boundary data files are available to permit mapping and spatial linkage operations.
• Interaction datasets describe the flows between different geographical areas in terms of migration and travel to work and these are known as the special migration statistics and special workplace statistics respectively.
• Microdata (records relating to individual persons) are available as Samples of Anonymised Records, the more detailed of which can only be accessed in a secure setting.
• Government and academic users can apply for research access to the ONS, Scottish and Northern Ireland Longitudinal Studies, which link small samples of anonymised records between censuses and certain key administrative sources such as birth, death and cancer registers (exact details vary by country).

In general terms, greater statistical detail is available for larger geographical areas and for more recent censuses. Detailed digital information is available for small areas from 1971 and for medium-sized areas for some early censuses. The most limited information is currently available for censuses from the early and middle decades of the Twentieth Century, which predate computerized small area data production but for which the individual records remain subject to a 100-year confidentiality rule. There is considerable interest in the individual records from censuses over 100 years old for genealogical purposes and several early censuses have been digitized.

Detailed arrangements for access to census data vary by sector, with UK academic users having the most extensive range of online access. The SASPAC consortium provides the principal modern datasets in conjunction with its SASPAC software and basic counts from the 2001 censuses are available online from the national census organizations' own websites. The census organizations provide fuller datasets free of charge on CD/DVD but these are generally only suitable for the more expert user who is able to extract the specific information they require from the bulk data tables. A range of value-added resellers provide census data customised to users' needs on a commercial basis.

UK academic access to all the key census datasets is via the ESRC Census Programme Portal at http://census.ac.uk/ and the principal public sector software for accessing census data is that provided by SASPAC http://www.saspac.org/. Users wishing to obtain historical census datasets are referred to the National Archives http://www.nationalarchives.gov.uk/census/ and also the Vision of Britain website http://www.visionofbritain.org.uk/.