A single standard output geography has been adopted for the 2001 Census results called Output Areas. These follow more closely the model used by Scotland in the 1991 Census; the geography matches the postcode geography wherever possible and is designed to different criteria to the design of the collection geography.
An Output Area (OA) is the smallest geographical unit for which census data can be published. For the 2001 Census there are approximately 200,000 OAs is England and Wales, 35-38,000 OAs in Scotland and around 7,500 OAs in Northern Ireland.