Output Areas (OAs), Middle layer Super Output Areas (MSOAs) and Lower layer Super Output Areas (LSOAs) are all geographical areas originally derived for the presentation of the Census data in 2001, but have subsequently been used as geographical areas for other indicators such as the Index of Multiple Deprivation which is available at LSOA geographical level.
The most commonly used area among these three geographical areas are LSOAs, although the MSOAs are sometimes used as an alternative to wards as they are a similar size (if ward data is not available) and some data has been represented at OA level from the 2021 Census.
OAs, MSOAs and LSOAs were first derived nationally following the 2001 Census. Prior to that, information was often presented at ward level, but the population size within wards across the entire country varied dramatically, which meant that the statistical certainty differed considerably, and in some cases, numbers were too small to present the information for some of England’s smallest wards.
LSOAs are made up from MSOAs, and MSOAs are made up from OAs.
Output Areas (OAs) are the lowest level of geographical area. They are made up from between 40 and 250 households, and usually a resident population between 100 and 625 people, although there are exceptions, for instance, where there is a large prison. Following boundary changes in the 2021 Census, there are now 881 OAs in Hull.
The LSOAs are made up from groups of OAs, generally four or five.
The boundaries of each LSOA were created so that each LSOA in England has a minimum population of 1,000 residents and an average of 1,500 residents, and generally between 400 and 1,200 households. There are currently 33,755 LSOAs in England (following the 2021 Census), and 168 LSOAs in Hull.
The MSOAs are made up from groups of LSOAs, generally four or five.
MLSOAs comprise between 2,000 and 6,000 households and usually have a resident population between 5,000 and 15,000 with MLSOAs fitting within local authorities. There are currently 6,856 MLSOAs in England.
Further information about the changes in the LSOAs following the Censuses is given on Lower Layer Super Output Areas.
Also see Index of Multiple Deprivation.