Beyond 2021 – transforming the Census

The 2021 Census will be the UK’s first predominantly online census. For future decades ONS is exploring the possibility of a Census based on linking together administrative data  supported by survey information.

Becky Tinsley reflects on how ONS is refining its approach to gathering and using administrative data – information people have already supplied to other government bodies – to produce census-type outputs.

In February, we talked about our aim of putting together a census based on combining administrative data and surveys. We call this an Administrative Data Census.

To understand how well we’re progressing towards this, we carry out an assessment each year. Today we’ve published our second annual assessment.

Our assessment is made against the following five high-level criteria:

These criteria reflect what needs to be in place for the Office for National Statistics (ONS) to move to an Administrative Data Census.

Figure 1 shows the assessment we’ve published today. It shows where we were last year, where we are now and where we expect to be by 2023. Understanding where we expect to be by 2023 is important as that’s when the National Statistician will make the next recommendation about the future of the census and population statistics.

Our expected assessment shows the real potential to move in a different direction after the next census in 2021. We also show the direction of our progress from last year, and the progress we expect to make in the coming year.

Figure 1. Overall assessment against five high-level criteria 


The major change from last year’s assessment is on access to data. This is due to the Digital Economy Act 2017 being passed into law in April 2017.

The Act gives ONS a right of access to information held by government departments, other public bodies, charities and large and medium-sized businesses, for statistics and research purposes. This is an important step forward in our ability to access the range of data needed to produce Administrative Data Census outputs.

While this is the only criteria we’ve changed our assessment for since 2016, we’ve made good progress towards improving our assessment for other criteria. In our previous blog we talked about the progress we have made in:

One of our biggest challenges will be to produce outputs about the characteristics of our population and housing stock.

The ten-yearly census produces vital information on a range of topics (such as ethnicity, labour market, education, health) to plan services, evaluate policy and allocate resources. In the last year, we’ve explored what administrative data is available for each of the census topics. We’ve made an initial assessment of the coverage (how much of the population is covered) and the quality (how closely does the administrative data meet the user need) of each topic, as shown in figure 2.

For some topics (such as age, sex, accommodation type and number of bedrooms), administrative data is available that covers the majority of the population and is closely related to the user need. For example, almost all of the data sources we have access to include date of birth and sex. These include the NHS Patient Register, Department for Work and Pensions (DWP) Customer Information System data and School Census data. The Land Registry and Valuation Office Agency data sources both include ‘type of property’ and ‘number of bedrooms’ information that covers most of the housing stock in England and Wales. We therefore expect to be able to produce our outputs directly from administrative data for topics like these.

For other topics (such as the amount of unpaid care provided), there is very limited administrative data available. We would expect to rely more heavily on surveys to produce these outputs.

Figure 2. Quality assessment of census topics from administrative sources

Our plans for the next year build on this ground work. We’ll continue to demonstrate the potential for an Administrative Data Census to produce outputs that meet information needs by publishing more Research Outputs.

We’ll also work closely with data suppliers to access data sources through the new powers in the Digital Economy Act 2017. The Act will enable us to make progress against the other high-level criteria over the coming years and building those relationships with suppliers will be crucial if we want to move to an Administrative Data Census post 2021.

Becky Tinsley is Acting Head of Administrative Data Census