Census Output Area Classification, 2001

The 2001 Output Area (OA) level Classification places each OA in the UK in a group with those other OAs that are most similar in terms of socio-economic and demographic census variables taken from the Key Statistics tables. This enables similar areas to be classified according to their particular combination of characteristics. The Output Area Classification has been constructed by creating a hierarchy of clusters, which together typify the characteristics of a given area. There are three layers of the classification that make up the hierarchy. The three layers are: 7 Supergroups (first layer); 21 Groups (second layer); 52 Subgroups (third layer). The Groups and Subgroups within a Supergroup provide more specific detail about the members of a Supergroup.

The data consists of 18,200 Output Areas along with the 41 variables used to create the Output Area level Classification and their corresponding values. The files are arranged by Government Region (in which Scotland, Northern Ireland and Wales are single and separate regions). In addition there is a Distance from Clusters file containing the distance (SED) for each OA to the Supergroup/Group/Sub-group centre.


Details of other sources of Census data from the UK

Spatial Coverage: 
United Kingdom
Data Creator: 
Office for National Statistics.
Time Period: 

Based on areas at time of Census, 29 April, 2001. Data released November 2006.


Documentation is available on the CD-ROM and from Area Classification for Output Areas on the ONS website, and includes:

  • Cluster Summaries consisting of details of each of the 7 Supergroups in PDF
  • a Cluster membership file consisting of a look-up table of OAs to Supergroup/Group/Sub-group
  • a Methodology paper file in PDF
  • a Variable Selection file in PDF giving details about the choice of variables used for analysis in classification
  • a 2001_Classifications.chm file detailing comparability of variables etc. with the 1991 census

The Social and Spatial Inequalities (SASI) website at the University of Sheffield is hosting the classification in conjunction with National Statistics Online. It is also designed to give users access to the classification and information about its creation and additional information to aid use.

File Descriptions: 
  • Cluster summaries in PDF format.
  • Classification membership files in Excel format.
  • Data files in Excel format.
  • Distance from clusters files in Excel format.
  • GIF image files.
  • Map files in PDF format.
  • Dreamweaver readable style sheets
  • Variable selection files in PDF format.
  • Classifications help files in Microsoft HTML.
  • Methodology files in HTML.
  • Conditions of supply information files in HTML.


File Storage: 

Written to CD-ROM 16/02/07.


MS-Excel format. Data can also be downloaded from: Area Classification for Output Areas on the ONS website

Data Access: 

Data available free from internet. Alternatively Edinburgh University users may contact the Data Library for access.