Data on an individual’s sex is a commonly asked for or recorded variable in official statistics. Some producers of statistics are making changes, or considering making changes, to the data they collect and report about sex. This guidance details what producers should consider when collecting and reporting data about sex, to meet the expected standards of trustworthiness, quality and value, as outlined in the Code of Practice for Statistics.

As the regulator of official statistics, it is not for us to define what data about sex are collected across the statistics landscape. The UK statistics landscape is complex, with a variety of different data and statistics being produced. Equally, the needs of people using data and statistics can be extensive and varied. This means there can be valid reasons to produce measures based on different classifications or definitions depending on the question the producers are trying to address through the statistics. Our role is to ensure that statistics serve the public good and meet society’s needs for information; we do this by ensuring statistics producers develop and produce statistics in line with the Code.

Work is underway across the Government Statistical Service (GSS) to develop and support the use of harmonised measures of sex and gender in data collection across government. Some of this work will include guidance on what form of data collection and disaggregation is most appropriate in different circumstances. The Office for Statistics Regulation (OSR) supports this work and will continue to engage with producers as it develops.

OSR’s expectations of producers when collecting and reporting data about sex

As a producer, if you are currently collecting and reporting data on sex or are considering making changes to how you do so, it is important that you do so with clarity, being transparent about the reasons for your judgements and decision making throughout. You should explain to users what and how data are being collected and support the appropriate use of the statistics.

Below we summarise our expectations of producers when collecting and reporting data about sex, under each pillar of the Code.


  • The collection and reporting of statistics about sex should support a legitimate public interest and be done in the least intrusive way. Those producing and releasing statistics should be impartial and independent and demonstrate sound judgement.
  • Producers need to understand what data they can legally collect about an individual’s sex and comply with relevant legislation, as well as considering any relevant nationally- and internationally-endorsed guidelines.
  • The privacy and identity of individuals must be protected at all times during data collection, storage, analysis and reporting. This includes being clear and open with individuals providing information about how their information will be protected, applying relevant security standards to keep data secure and using appropriate disclosure methods when releasing statistics.
  • Producers should understand the public debate on data about sex and ensure their statistics stay relevant to a changing society. This means statistics should be regularly reviewed, with users and other stakeholders involved to help prioritise any development plans. Where producers identify user needs that may be impacted by how data on sex are collected, they should consider how they can meet those needs in their work programme, working collaboratively where appropriate, including with relevant subject experts.


  • Producers need to ensure data and statistics stay relevant to a changing society and are of sufficient quality. This means that the statistics should be based on appropriate data and methods.
  • Producers must have a good understanding of, and clearly explain, the sources of data about sex they are using and how these are collected. This applies to survey and administrative data sources; both the question(s) used, and the way that these are completed (i.e. whether data are self-reported or completed by another individual – an interviewer or an operational official, for example) can influence the exact nature of data collected and whether this is a mixture of sex registered at birth, self-identified sex, lived gender and others.
  • Producers should ensure that data are collected in a respectful way and understand any risks to data quality or survey response when asking for sensitive information from a person.
  • Producers cannot always design or change administrative systems which enable public services to be delivered. But they should seek to understand the systems, including any risks and biases that may arise from the way the systems collect and categorise data.
  • Uncertainty in the source data should be identified and the extent of any impact on or limitations of the statistics should be clearly reported. For data about sex this may be particularly relevant when considering data at smaller sub-group levels.
  • Producers should be clear about definitions or terminology they use, and these should be harmonised to be consistent and coherent with related statistics and data where possible. The terms ‘sex’ and ’gender’ should not be used interchangeably in official statistics.


  • Statistics should meet their intended uses and should inform public debate. To achieve this, producers must seek to understand their whole user base and the questions that users want to be able to answer with their statistics.
  • Where an evolving or new user need has been identified, statisticians should consider whether the data that inform the statistics can and should be enhanced to better capture this information. This could mean, where feasible, seeking to build relationships with external data suppliers so that producers have the opportunities and means to influence data collections. Where a user need cannot currently be met, producers should explain why this is the case, and anything that can be done to help these users.
  • Decisions about whether to continue, discontinue or adapt statistics about sex should be made in discussion with users and other stakeholders. If a change is made to data collection, or if information about a data collection practice emerges which makes it clear that the nature of the data may have been previously misunderstood, a clear explanation of the change should be published, with evidence of the rationale and, wherever possible, the analysis that informed the change.
  • Collection and reporting of data about sex is a sensitive and potentially divisive topic and there may be times when producers are unable to meet the requests of everyone who has an interest in their statistics. In these cases, it is more important than ever to be transparent and open about the decision-making process and the evidence used to inform the choices that have been made, particularly in relation to any areas of contention.

A worked example: recording and reporting of sex in criminal justice statistics

Criminal justice statistics are important statistics which help the public understand the nature of incarceration in their country.

There are examples within official statistics relating to criminal justice across England and Wales and Scotland where breakdowns of the data are presented by sex, with data marked as ‘female’ and ‘male’. The data used to produce the statistics comes from the court system in each country. It is recorded by an operational officer and this means there can be variation in the way data about sex is captured across the system. This means it is not possible to know what definition of sex is being captured. This can, in turn, place limitations on how some criminal justice statistics can be interpreted and used.

In this instance, it is hard for the statisticians to change the administrative systems, but they can understand them. OSR would expect producers of the statistics to:

  • understand the nature of the data they are currently using to produce their statistics
  • clearly state how data about sex are gathered
  • clearly explain any terminology in the statistics – the Ministry of Justice does this well in its Statistics on Women and the Criminal Justice System publication, and in the associated technical guide
  • have robust quality assurance measures in place
  • clearly explain any limitations of the data and the impact these have on the statistics and their use. In addition, we would encourage producers to build relationships with their data suppliers, so that they can have the conversations to seek change where there is an identified need, and it is feasible

Finalising the guidance

We published this guidance on collecting and reporting data about sex in official statistics as draft and welcomed comments from statistical producers and other stakeholders. Thank you to those who shared your views with us.

We are currently reviewing this guidance, please see here for more details

If you have any questions, queries or further feedback as we go through this process we would be happy to hear from you. Please email us.