1. Introduction

Background to the statistics

1.1 The gender identity question was asked for the first time in the 2021 England and Wales Census, conducted by the Office for National Statistics (ONS). The question represents the current Government Statistical Service harmonised standard in development for collecting data on gender identity. The question asked, “Is the gender you identify with the same as your sex registered at birth?”, with those who answered ‘no’ being asked to write in their gender identity. The question was voluntary and asked only of respondents aged 16 and over.

1.2 Measuring gender identity is undoubtedly challenging. It is inherently personal and therefore can be a sensitive topic. Those whose gender identity differs from their sex represent a small proportion of the population which creates challenges for data collection. The concept may be unfamiliar to many people and that there are few robust alternative sources of data to cross-check against.

1.3 The first release of statistics on gender identity based on Census data was in January 2023. This led to some concerns being raised with ONS and the Office for Statistics Regulation (OSR) regarding the correlation of gender identity with other characteristics (in particular English or Welsh language proficiency), as well as the level of methodological information published on how the gender identity question has been processed.

1.4 The subsequent datasets showed that those aged 16 and over whose main language is not English (or Welsh if using Welsh questionnaire), made up 10 per cent of the overall population, but 29 per cent of those whose gender identity differed from their sex registered at birth. The data showed that areas with the highest proportion of people reporting themselves as transgender were areas that also had a high proportion of people whose first language is not English (or Welsh). This led some users to conclude that the question on gender identity may have been misunderstood by those with lower English language proficiency. Michael Biggs, Associate Professor in Sociology at the University of Oxford, explored some of these concerns in a Spectator article.

1.5 ONS initiated research in response to these concerns in April 2023. We then announced our plans to carry out a short review of these statistics and the findings of ONS’s research, formed around the principles within the Code of Practice for Statistics. The review considers ONS’s approach to responding to questions raised by users about the results of the gender identity data. It does not consider gender identity as a concept or the decision to collect data on gender identity. We published our emerging findings as part of a letter to ONS on 19 June, this interim report builds on those findings and should be considered our current view.

Our review

1.6 Our review was based on desk research of information in the public domain and stakeholder engagement in the form of interviews. These interviews were carried out with teams in ONS involved in the question design, testing and analysis of the gender identity data collected in the 2021 Census. We also spoke to several users of these statistics. Where possible, ONS has also shared updates on its ongoing research to inform our review. ONS’s openness with us has been very useful in informing our own research, and we are very grateful for the approach it has taken in sharing these updates.

1.7 This interim report sets out our expectations of what is needed from ONS to provide assurance on the gender identity data and harmonised question in line with the Code. We have based these on what we know so far on how ONS tested, quality assured, communicated and engaged with users, both in advance of publishing the results and where appropriate from the research to date.

1.8 We will publish a final report following publication by ONS of its research reports. These outputs have been postponed twice, having been preannounced for June and then August. We expect ONS to take on board the findings and recommendations set out in this interim report as it works on developing the research reports for publication.