Secure microdata

The secure microdata files consist of random samples of 10 per cent of people or households in the 2011 Census output database for Northern Ireland.

There are two secure microdata files:

  • an individual file which includes person level data on over 220 variables for over 180,000 individuals. The lowest level of geography available is Local Government District (LGD). Records include those resident in households and communal establishments
  • a household file which includes person and household level data on over 200 variables for over 180,000 individuals within more than 74,000 households

User Guide

More information on the secure microdata files is available from the:

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 will be only available to approved researchers via the NISRA secure environment. Other arrangements are being made across the rest of the UK.

To get access to the secure microdata files you will need to:

1. Formulate your research proposal

Researchers should contact the NISRA Research Support Unit (NISRA-RSU) to discuss whether their research question of interest can be explored using the 2011 Census secure microdata samples. The NISRA-RSU is happy to provide feedback by email, telephone or to facilitate a meeting to discuss the feasibility of a potential project.

Details of all available 2011 Census secure microdata variables are available from the:

All proposals must meet the criteria outlined within the:

2. Complete and submit an application form

Researchers must then complete a Census Secure Microdata Application Form which will include details about the researchers involved, project description, research aims, sample population, variables to be included and dissemination/publicity strategies. Researchers should submit their application form to NISRA-RSU.

Further information on how to complete an application form will be available shortly.

3. Complete a Census Agreement Form

If a Census project is approved, a Census Agreement Form must be signed by the Chief Investigator and all other research applicants. An Institutional Signatory will also be required by a representative(s) for the organisation(s) with ultimate responsibility for research team members.

The Census Agreement Form contains the Census Confidentiality Undertaking, Census Disclosure Control Policy, Census Licence Agreement and Census Publication Policy.

4. Become an approved researcher

Researchers must attain Approved Researcher status by completing the Application for Accreditation as an Approved Researcher Form. The form asks for details of experience and professionalism and will be used by senior NISRA staff to approve the researcher as a 'fit and proper' person. Further details on the Approved Researcher application process are available from NISRA-RSU.

5. Complete safe researcher training

All researchers named on a project, who wish to access data within the secure environment, must complete Safe Researcher training and pass the related online test. Further details on training can be found in the Accredited Researcher Process on the NISRA website.

6. Obtain BPSS security clearance

All researchers who wish to access data within the secure environment are also required to have Baseline Personnel Security Standard (BPSS) clearance.  To be granted BPSS clearance, researchers must supply NISRA-RSU with a valid AccessNI Disclosure Certificate.  Further information on the application process can be found in the Accredited Researcher Process on the NISRA website.

Data analysis

All primary data analysis will be carried out within the secure environment in NISRA Headquarters, Colby House, Belfast where the 2011 Census secure microdata samples are maintained. Researchers within the secure environment will be supervised at all times by NISRA-RSU staff who will also be available for help and advice.

The main data analysis software packages are normally available (SPSS, STATA, MLWin, R and the main Microsoft packages).


Outputs from analyses will normally be released from the secure environment (via email) once checked for disclosure risk and cleared by the NISRA-RSU in accordance with the Census Disclosure Control Policy contained in the Census Agreement Form. Currently a frequency of 10 is the minimum count permissible in any outputs which is to be removed from NISRA premises. Intermediate outputs cannot be released to any other individual(s) or organisation(s) not named on the approved Census Secure Microdata Application Form and Census Licence Agreement (as contained in the Census Agreement Form).

Researchers should allow a maximum of 5 working days for the clearance of an intermediate output.


To disseminate project results beyond the named project team (named in the Census Secure Microdata Application Form and Census Agreement Form) clearance must be obtained from NISRA-RSU. This reduces the risk of disclosure, ensures that the data are properly described, the data have been used appropriately and the approved acknowledgement is used. Examples of final outputs are working papers, reports or journal articles intended for publication, presentations or abstracts.

Researchers should allow a maximum of 20 working days for the clearance of all final outputs, with the exception of conference/journal abstracts, for which 5 working days are required. Researchers must notify the NISRA-RSU when a presentation/publication has been delivered or published.