The Sullivan review, commissioned under the last Conservative government, has shown how biological sex has been erased from official data and that the meaning of sex is ‘no longer stable’ in administrative or major survey data.
This instability is evident across key policy areas including health and justice and has led to a “widespread loss of data” on sex.
The study, led by Professor Alice Sullivan from University College London, investigated all public bodies and found that how sex is defined is rarely made apparent in published outputs, including official statistics.
It found data collection practices do not meet the standards set out by the Office for Statistics Regulation for collecting and reporting data about sex and gender identity in official statistics.
These standards state that data about sex and gender identity “should be explained and defined for the purpose of a particular set of statistics, and terms, including gender, should not be used interchangeably or as a substitute for each other”.
The Sullivan Review found the loss of data on sex was a relatively recent phenomenon. Its analysis showed the term “gender” gained traction as a synonym for sex in the 1990s.
More fundamental changes have taken place within the last decade, which has seen both the reframing of “gender” as a synonym for gender identity, and the replacement of sex questions with gender-identity questions.
Sullivan said in the review: “Both people’s material circumstances and their identities are important to their lives. Sex and gender identity are distinct characteristics and therefore should not be treated as substitutes.
“This should not be seen as a zero-sum game between characteristics. We can and should collect data on both. Stakeholders across the board, including representatives of LGBT+ organisations, have told us that they understand the need for data collection on sex.”
She added: “If we acknowledge that gender identity and sex are distinct concepts, this gives us a way forward which allows us to collect the data we need for all characteristics. Acknowledging sex does not erase gender identity or vice versa.”
The Sullivan review made key recommendations, including:
- Data on “sex, age and ethnic group should be routinely collected and reported in all administrative data and in-service process data, including statistics collected within health and care settings and by police, courts and prisons”, in line with UK Statistics Authority recommendations.
- The default target of any sex question should be sex, ie, biological sex.
- As sex and gender identity are distinct concepts, questions which combine sex and gender identity in one question should not be asked.
- The word ‘gender’ should be avoided in question-wording, as it has multiple distinct meanings, including: a synonym for sex; social structures and stereotypes associated with sex; and gender identity.
- The NHS should cease the practice of issuing new NHS numbers and changed ‘gender’ markers to individuals, as this means that data on sex is lost, thereby putting individuals at risk regarding clinical care, screening, and safeguarding, as well as making vital research following up individuals who have been through a gender transition across the life course impossible. In the case of children, this practice poses a particularly serious safeguarding risk, and should be suspended as a matter of urgency.
- Data providers often default to using ONS Census questions. However, the ONS 2021 Census question “Is the gender you identify with the same as your sex registered at birth” has been shown to be flawed. This question, and variants of it, should not be used.
The review found several surveys administered by the Ministry of Defence that only collect data on gender identity. For example, a sexual harassment survey by the Royal Navy did not collect data on sex, “despite its obvious relevance to the subject matter”. Instead it asked “do you identify as” male, female, or nonbinary.
The annual NHS staff survey, one of the largest workforce surveys in the world, stopped collecting data on sex in 2017, and in 2023 asked, “What of the following best describes you” with options including non-binary and “prefer to self-describe”.
‘Sex pay gap reporting’
The review found that “gender”, previously a polite synonym for sex, now has multiple distinct meanings. Legislation referring to gender is now open to misinterpretation, even in cases where it may appear clear that, at the time the legislation was enacted, gender meant sex.
Sullivan said: “When reporting on or discussing issues relating to sex, it would be desirable to see a shift to using the term ‘sex’ instead of gender, given the ambiguity of the term ‘gender’. This should be reflected in government language and guidance. For example, guidance for employers on ‘gender pay gap’ reporting should refer to ‘sex pay gap’ reporting.”
She added that UK government guidance states that employers “should be sensitive to how an employee identifies in terms of their gender” and that “where the employee does not self-identify as either gender, an employer may omit the individual from the gender pay gap calculation”.
This should not be seen as a zero-sum game between characteristics. We can and should collect data on both. Stakeholders across the board, including representatives of LGBT+ organisations, have told us that they understand the need for data collection on sex” – Prof Alice Sullivan, UCL
This means that gender identity is recorded rather than sex, and employees who identify as non-binary are excluded from the data, making it impossible to assess whether non-binary males may have different labour market experiences from non-binary females.
A government spokesman said: “This government is clear that the collection of accurate and relevant data is vital in research and the operation of effective public services, particularly when it comes to sex.
“We are grateful to Professor Sullivan for her work, which has been shared with relevant government departments and public organisations, including the ONS.”
‘Destruction of data’
Maya Forstater, chief executive of campaign group Sex Matters, said: “This review is devastatingly clear about the harms caused by carelessness with sex data and a decade-long failure of the civil service to maintain impartiality and uphold data standards. The destruction of data about sex has caused real harm to individuals and research, and undermined the integrity of policy-making.
“The problems are everywhere, from NHS records that do not record biological sex to police forces that record male sex offenders as women. Conflating sex and gender identity is not a harmless act of kindness but a damaging dereliction of duty.
“These corrupted data standards have been set by bureaucrats insulated from the impact of their decisions, and competing for Stonewall awards.
“The government should swiftly implement the recommendations of the Sullivan Review in order to restore administrative integrity in every place the state collects data on the sex of its citizens.”
Keyne Walker, strategy director of campaign group TransActual, said: “These recommendations would do nothing to support the government’s stated objectives regarding equality and diversity nor on data use. It represents a deviation from the government’s stated position, and would be a U-turn should it be implemented.
“Worse, the experience of those working in the field suggests that far from improving data quality, the measures promoted by this report would make data collected on sex and gender far less reliable.”
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