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ONS is aware of the importance to users of samples of anonymised records (SARs) and is confident that fit-for-purpose, appropriately accessible UK microdata files will be made available in 2014.

Three levels of microdata are planned for 2011 Census:

Teaching file

The teaching file is now available.

Formerly called the Public Use file, the primary aim of the teaching file is as an educational tool. The release of this non-disclosive, individual-level file is in line with the government transparency agenda. It is less detailed than the file made available under end-user licence in 2001.

Safeguarded files

One type of safeguarded file will be at the individual person level, and it is intended that this will be made available to users via their desktops (precise details of the conditions are being finalised). The file is likely to contain a similar level of detail to the 2001 small area microdata, and the individual level SAR, with a maximum sample size of 5 per cent.

ONS also intends to is also looking at the feasibility of releasing household hierarchical data containing records for all individuals, within a sample of households. All files will be subject to being able to apply sufficient disclosure control.

Secure files

These anonymised data will be held in a secure environment, ONS's Virtual Microdata Laboratory (VML). They will generally be similar to the 2001 Controlled Access Microdata Sample (CAMS), both household and individual, and will contain a maximum sample size of 10 per cent.

To see the planned microdata product table, download proposed 2011 microdata products (19 Kb Excel sheet) .

The remaining 2011 Census microdata files will be made available later in 2014. ONS is continuing to work with users to develop and agree the specifications and access arrangements for the safeguarded and secure microdata products, with the aim of further releases later in 2014. The secure files will be published first, followed by the safeguarded.

Planned features include microdata sets with sample sizes larger than previous censuses, the opportunity for exploratory analysis on rich and flexible datasets, the opportunity to test outputs before requesting commissioned tables, and the ability to perform multivariate statistical analysis, all using records that are comparable with the standard census outputs, since they have the same source. 

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