Output areas (OA) are created for Census data, specifically for the output of census estimates. They play a key role in the reporting of statistics and are the building blocks for calculating values for many larger geographies.
They were first introduced in England at the 2001 Census. 2001 Census OAs were built from clusters of adjacent unit postcodes, but as they reflected the characteristics of the actual census data they could not be generated until after data processing. They were designed to have similar population sizes and be as socially homogenous as possible, based on tenure of household and dwelling type.
The minimum OA size was 40 resident households and 100 resident people but the recommended size was substantially larger at 125 households. These size thresholds meant that unusually small Wards and Parishes were incorporated into larger OAs.
Super Output Areas
ONS have introduced Super Output Areas to replace electoral wards as the standard geography for the collection and dissemination of small area statistics. In the past electoral wards formed the geography for the targeting of funds and grants by the government and other agencies this role now rests with SOAs.
For more details on Lower Layer Super Output Areas (LSOAs) and Middle Layer Super Output Areas (MSOAs) follow the links in the left hand menu.
For more information on Super Output Areas follow the link below to the Super Output Areas (SOAs): Frequently asked questions section on the Office of National Statistics Website.
Super Output Areas
2011 Census Boundary Changes
Maintaining stability as far as possible was key for the 2011 Census. A key principle of OAs is that they are not subject to the frequent boundary changes which cause problems when using electoral wards to present statistics. This will provide a stable base on which to compare statistics over time. There will be a need, however, to change OA boundaries in the exceptional cases where there has been significant population change, as recorded at each Census. These OAs will either be split (if the population has become too big) or merged with a neighbouring OA (if the population has fallen below an acceptable threshold).
There are now 181,408 OAs, 34,753 LSOAs and 7,201 MSOAs in England and Wales. Significant points of interest for the 2011 Census are that OAs and SOAs align to local authority boundaries, including those that changed between 2003 and 2011. The average population in an OA has increased from 297 in 2001 to 309 in 2011. In Staffordshire there is a total of 2,759 Output Areas.