May 2016 - Researchers drawing data from the 2011 Census can apply to access two secure England and Wales (E&W) microdata samples, two secure Northern Ireland (NI) microdata samples, and two secure Scottish microdata samples. These consist of (non overlapping) random samples of 10 per cent of people or households in the 2011 Census output databases for England and Wales (combined), Scotland, and Northern Ireland.
There are two types of secure microdata files.
1 - An individual file
The England and Wales file includes person-level data on 258 variables for over 5 million individuals; the lowest level of geography available is local authority. The Northern Ireland file includes person-level data on over 220 variables for over 180,000 individuals; the lowest level of geography available is local government districts in Northern Ireland. The sample for Scotland includes person-level data on 146 variables for over 534,000 individuals, and the lowest level of geography available is council area. Records in these sample files include those persons resident in households and communal establishments.
2 - A household file
The England and Wales file includes person- and household-level data on 245 variables for over 5 million individuals within more than 2.4 million households. The Northern Ireland file includes person- and household-level data on over 200 variables for over 180,000 individuals within more than 74,000 households. The Scotland file includes person and household-level data on 220 variables for over 524,000 individuals within more than 247,000 households.
Information on the Northern Ireland files is available, as well as information on the samples drawn from the 2011 Census output database for Scotland.
How to access the data
The secure microdata files represent the products with the highest level of detail and the largest sample size. They are protected by the highest level of access limitation and initially are available only to those assigned by ONS as Approved Researchers. Access to Census microdata samples is via the Secure Research Service (SRS) facilities at ONS sites in Newport, Titchfield, and London. Access to secure microdata samples for Northern Ireland only are also available to approved researchers via the NISRA secure environment; see the NISRA website for more on accessing that data. NRS is currently investigating options for providing researchers with access to secure census microdata products for Scotland in additional secure environments.
Find out how to be accepted as an Approved Researcher. Applications for access data held at ONS can be emailed to the Research.Support@ons.gov.uk. The process to approve projects, receive training and gain access to the secure data in the VML will take approximately two to three weeks depending on the level of demand.
- Secure Microdata User Guide (622.1 kB pdf)
- Person sample code book (2.9 MB xls)
- Household sample code book (7.5 MB xls)
- Quality document - comparing the sample with published data (404.0 kB xls)