2011 UK Census

A base building block - the Outputs Areas (OAs) - were created using Census data, with other spatial datasets used to constrain the OA shape.

OAs were designed to have

• roughly similar populations (a target of 125 households)
• lower thresholds - to prevent them having too few people/households and therefore risk being disclosive
• upper thresholds - to prevent them having too many people/households
• as much social homogeneity as possible, based on tenure and accommodation type

OAs were then used to produce 2001 Census results for the range of standard statistical geographies. In 2004 they were aggregated into layers (lower and middle) of Super Output Areas (SOAs) which have become well-established and used widely beyond the Census.

In early 2007, the ONS ran a Consultation on Small Area Geographies (England and Wales) to gather user feedback and opinion about the use of OAs and SOAs. The full consultation report can be viewed here .

The results have been used to inform a maintenance strategy for OAs and SOAs in 2011. The aims are to

• retain a high degree of stability at both the OA and SOA level
• make minimal changes to 2001 OAs/SOAs to take account of significant population changes to OA/SOAs since 2001
• assess methods of merging/splitting OAs/SOAs
• secure similar licensing arrangements to 2001 for sharing and distributing OA/SOA boundaries created for 2011, and for commercial use of OA/SOA boundaries
• try to align the Scottish and English OAs at the border
• provide additional mean-high-water boundaries so that familiar coastlines are displayed
• see how feasible it is to automate aligning OA boundaries to real life features without affecting their population

Work to develop the finer details and supplement this high level plan is continuing in parallel with ongoing output consultation with users.

Many issues highlighted in the 2007 consultation were a product of the automated process that had to limit the amount of constraining data in zone creation used for 2001 OA production. Some of these issues will be investigated by an ESRC funded project by Southampton University, supported by ONS.

Continuing until May 2009, the project will evaluate methods using automated zone design for maintaining OAs and SOAs for 2011. It will create automated procedures for splitting, merging or re-designing 2001 output geographies, for use in 2011, without affecting their populations or significantly increasing any licensing costs.

The results of this study will be used to inform policy for 2011 and possibly to consult further.

We already have some user comments about OA use for 2011, and as ever, are always happy to

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