The 2021 Classification for Output Areas (2021 OAC) is a hierarchical geodemographic classification across the UK which identifies areas of the country with similar characteristics. The classification contains the following breakdown of Output Areas into 8 different supergroups, into which are nested 21 groups and and 52 sub-groups.
UK-OAC Modelled is a full-area-coverage interim release of 2021 OAC, covering the whole of the UK. Because the Census 2021 in Scotland was delayed until 2022, and the resulting small-area aggregate Scottish statistics have not yet been published, this version of OAC includes modelled data for Scotland and Northern Ireland (which has had a slower release schedule compared with England and Wales). Please see the linked academic paper for details of the modelling that was applied. Subsequently, a UK-OAC finalised version, using only actual data, has been provisionally released.
This product has identical subgroups, groups and supergroups to the Output Area Classification 2021, and the classification result for England and Wales is also identical. The Output Area Classification 2021 has been separately released in partnership with the Office for National Statistics as an Open product and is available via the Related Record link below.
This interim version of the classification has now been replaced with a real-data version covering the whole of the UK. It is retained here as a record for research reproducability purposes, but applicants will be directed to the real-data version unless it is specified in the project text you need the modelled version.
To avoid confusion between the modelled-data and real-data parts of UK-OAC, the dataset itself has been retained as a Safeguarded-level dataset and is only available upon application through the normal GeoDS application process for controlled datasets.
If you need the data for just areas within England and/or Wales, you can download it directly from the Related Record below rather than applying for it here.
Content
The data are supplied in CSV format. Additional information about this data, including a classification typology, glossary of variables and terms, as well as distribution statistics, is available for download below. Classification codes and names can also be downloaded below.
Quality, Representation and Bias
As official government statistics, the quality of the indices is believed to be very high, and complete - covering every small statistical unit area of the United Kingdom at regular intervals. Each home nation tunes its version of the index to meet local needs, resulting in different emphasises (and so biases) for each nation.
As the Census in Scotland was delayed from 2021 until 2022, and small area outputs from Northern Ireland's Census were not available at the time of production of the classification, this data release covers used census and modelled estimates. A journal article accompanies 2021 UK OAC which provides a thorough evaluation and rationale for the approach. The classification was created using 2021 Census Output Area data for England and Wales; aggregate published 2021 Northern Ireland data, apportioned to 2011 small area census geography; and 2011 Scottish Census results carried forward in adjusted or unadjusted form.
In general terms, a geodemographic classification presents a best effort of the authors to represent the characteristics of the population and geographic context, however, there are decisions made during the classification process that guide these representations. Again for a full overview of these decisions and their rationale, see the published paper.
