Microdata products often contain many variables detailing associated census characteristics of both households and individuals, but they do not contain personal information that could identify any household or individual.

These products enable you to access data similar to that which you might collect if you were to conduct a survey yourself, and then you can analyse them in similar ways.

In 2011, we produced three types of microdata samples. These were:

  • a public-access microdata ‘teaching’ file (a 1% sample of individuals at region-level geography)
  • two safeguarded individual files (each a 5% sample of individuals, with one published with region-level geography and one with grouped local authority-level geography)
  • two secure files (one 10% sample of individuals and one 10% sample of households, both at local authority-level geography)

More recently, we have also made a ‘100% sample’ of 2011 microdata available in our Secure Research Service. This includes the full suite of data from the 2011 Census, including all variables for all individual and household records. However, only variables needed for specific projects are provided, and researchers may only apply to use these data if they can justify why the 10% household or individual samples are not sufficient (e.g. if they’re researching specific small populations).

Our plans for Census 2021

Following the census in 2021, we’ve been looking at creating similar microdata products to those produced in 2011. In addition to these, we’re also working with stakeholders to develop a safeguarded household file, which wasn’t available for 2011.

We’ve set up a microdata working group to work with expert users to inform our approach and design of microdata for the next census.

Finally, we’re also investigating the possibility of producing a file that will contribute to the University of Minnesota’s Integrated Public-Use Microdata Series (IPUMS) project. This is an international project that brings census microdata together from over 90 countries.

Accessing Census 2021 microdata

The ONS Approved Researcher process is changing and will now take place through an online application portal on the GOV.UK website. It should also allow you to connect to the Secure Research Service from a wider range of “trusted locations”.

This online service will enable prospective users to track the progress of their applications, book required training, and organise data access dates and locations.

More information

To find out more about census microdata, please email us at census.outputs@ons.gov.uk with your queries.