Census Output Areas (OAs) are small geographical areas that cover similar population sizes, according to the 2001 census, and are as socially homogenous as possible.

There are 165,665 Census Output Areas in England. The first six characters of this derived field represent the 2003 statistical ward.

The Census output area, 2001 (oacode) field contains sensitive data. Access to it requires the approval of the Security and Confidentiality Advisory Group (SCAG).