_Image: [Laurence Dutton](https://www.gettyimages.co.uk/detail/photo/box-checking-ticking-royalty-free-image/1359146574), via Getty Images_
**Study commissioned under Conservative government tracks changes in data collection since 1990s**
There has been a “widespread loss of data on sex” since the 1990s, according to an independent review carried out for the Department for Science, Innovation and Technology.
In February last year, Alice Sullivan, a professor of sociology at University College London, was commissioned to carry out a review of data, statistics and research on sex and gender by the then Conservative science secretary Michelle Donelan.
The review, published on 19 March, examined over 800 administrative and research datasets, surveys, and data collection policies, concluding that “the meaning of sex is no longer stable in administrative or major survey data”.
“This has led to a widespread loss of data on sex,” the review concludes, adding that in some cases this loss “poses risks to individuals” particularly in health and social care.
**Gender phenomenon**
The review also found that the loss of data on sex is “a relatively recent phenomenon”.
“Our analysis indicates that in the context of data collection, the term ‘gender’ gained traction as a synonym for sex in the 1990s,” the review concludes, adding: “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.”
Alongside Sullivan, the analysis was carried out by policy analysts Murray Blackburn Mackenzie and Kathryn Webb, a visiting academic at the University of Oxford.
**Sex data ‘by default’**
The review recommends that data on sex “should be collected by default in all research and data collection commissioned by government and quasi-governmental organisations”, and that the response categories should be either female or male.
“As sex and gender identity are distinct concepts, questions which combine sex and gender identity in one question should not be asked,” the review says.
The reviewers held over 30 stakeholder interviews with organisations including government departments, regulators, public sector organisations, fieldwork agencies, women’s rights campaigners and LGBT advocacy groups.
“Stakeholders have told us that they recognise the importance of collecting data on sex,” the report’s authors said, but that “confusion regarding the legal position has posed a barrier to collecting data on sex for some organisations”.
**Importance of identities**
The review acknowledges the importance of identities to people’s lives. “We know that sex affects many dimensions of people’s lives, and we have much to learn about the ways in which having a transgender identity matters too,” it says.
“Rather than removing data on sex, government and other data owners should collect data on both sex and transgender identities, in order to develop a better understanding of the influence of both factors and the intersection between them,” the review adds.
It says that “people with diverse gender identities are being let down by data collection practices which conflate sex and gender identity, making it impossible to track the outcomes of distinct groups”.