National Statistical

We are today sharing plans for our work to continuously improve the information available on gender identity statistics. This follows our request to reclassify our Census 2021 gender identity estimates to official statistics in development, which better reflects our developing understanding of measuring this complex and important topic. Here, Mary Gregory outlines what we are doing to support use of the existing gender identity data and our plans to review the standards for future data collection.   

For the first time, Census 2021 for England and Wales included a voluntary question on gender identity. This has provided a unique opportunity to learn more about collecting data on the topic in England and Wales, and has prompted valuable discussion about the strengths and limitations of the estimates. We are grateful to those, including the Office for Statistics Regulation (OSR), who have helped us build our understanding on this topic to date, and look forward to engaging with a wide range of stakeholders to inform our ongoing work.

While users have told us they value the data, we recognise there are limitations, and we need to do more to support the interpretation and appropriate use of the gender identity question and related estimates. We are now launching a new phase of work to improve understanding of uncertainty associated with the estimates and work towards an agreed harmonised standard for gender identity data collection.

As part of this, and following publication of Scotland’s findings on trans status or history, we have written to the OSR to request a change to the designation of Census 2021 gender identity statistics from accredited official statistics to official statistics in development to better reflect the innovative nature of the estimates and the evolving understanding of measuring gender identity. The new classification is also more consistent with the ‘under development’ status of the current harmonised standard.

OSR has confirmed the change and we welcome its final review of Census 2021 gender identity estimates, published today.

What does this mean for use of Census 2021 gender identity estimates?

We know there are varied users and uses of the Census 2021 estimates on gender identity, including to understand inequalities and inform service provision. While users have said they recognise there is uncertainty in these estimates, and tend to draw on the census outputs as one of a number of sources of information to inform decisions, it is also clear that they would welcome better guidance on limitations and appropriate use of the data. We will be providing more information to support this later this year.

As a first step, we will immediately review how users find the information on guidance and notes of caution on the existing gender identity pages on our website, making sure they are clear, consistent and accessible to all. We will then carry out further work to provide more detailed information on uncertainty associated with the estimates and guidance on their appropriate use.

In the meantime, we can draw on the evidence already available to support understanding. As outlined in November’s quality report, at the national level, comparable sources (NHS England’s GP Patient Survey, the Canadian 2021 Census and surveys in the United States), provide broadly consistent estimates.

This position has been mirrored in the more recently published data on trans status or history from the latest census in Scotland. Therefore, while there is associated uncertainty, we consider it should not be misleading to use the estimate from Census 2021 to give an indication of the trans population for England and Wales.

Scotland’s census analysis also added weight to the observation that there is potential for bias in how the gender identity question in England and Wales was answered by those who responded that they had lower levels of English proficiency, some of whom may have mistakenly given an answer suggesting they were trans. While relatively small, it will have greater bearing on the estimates at lower geographic levels, particularly where there are higher levels of non-English speakers.

This is one source of bias among a number. ONS has previously noted that as a voluntary question on a complex topic, being asked on the census for the first time, we would expect greater uncertainty than we see with other questions in Census 2021. ONS is unable to quantify the impact of all the sources of uncertainty to give an overall estimate of uncertainty. However, we can say that smaller group breakdowns should not be used as a precise estimate of the trans population and comparisons between areas or groups should be considered with caution, particularly where there are different levels of English language proficiency.

Given this challenge, we will look at a variety of approaches to support users to understand uncertainty and make appropriate use of the published data. This will include looking at sensitivity analysis and providing use cases with recommendations for appropriate use and limitations in different scenarios. We will engage with experts and users of these statistics to inform our approach and published outputs.

Future data collection on this topic

While looking at how to support use of the outputs from Census 2021 we will also be undertaking further collaborative work to identify the best approach to collecting data on gender identity.

The question from Census 2021 has been used in surveys within and beyond the Government Statistical Service (GSS) and we know there is a keen interest in what the best gender identity question is. The GSS harmonisation team provides advice on harmonised standards, developing questions and guidance to support consistency, coherence and comparability of statistics.

The current gender identity data harmonised standard, published in July 2020, was created using research and testing undertaken for Census 2021 in England and Wales. It was published as ‘under development’, acknowledging the need for further research to develop the standard. The GSS harmonisation team has previously published information on the strengths and weaknesses of the current standard. It notes the value of the comparability with Census 2021, but also the limitations including a lack of guidance for interviewers and the ability to process write-in data.

The latest update to the harmonisation team work plan set out its intention to share plans for its review before the end of 2024. This will be a thorough review of the current approach to measurement of gender identity which will inform future guidance, and will include consideration of survey and administrative data collection. It will draw on information made available since the standard was first developed, including the feedback we have received on the Census 2021 results, the work from the OSR, new insights from publication of Scotland census outputs and other emerging information.

Where possible we recommend waiting for the completion of the GSS harmonisation team’s work before deciding on the approach to measurement of gender identity. Where the current standard is being used, we encourage producers of statistics to clearly explain the associated limitations and appropriate use and to refer to the OSR’s guide to collecting data about sex and gender.

Get in touch

Our priority is to produce impartial statistics that best meet user needs. To achieve this, it is important we hear from a wide range of experts and users of our statistics. If you have any feedback or views, we’d like to hear from you.

If you are keen to be involved or want to understand more, please contact pop.info@ons.gov.uk