MBM response to the UK Statistics consultation on inclusive data (26 March 2021)

(Sent by email, 26 March 2021)

Dear Sir/Madam,

Since 2018 we have undertaken extensive research and analysis on data collection in relation to sex and gender identity. Our work includes both oral and written evidence to the Scottish Parliament on Scotland’s census, a peer-reviewed publication that traced the development of ‘self-identification’ guidance on the sex question in the UK censuses,[1] briefings, media articles and commentary.[2]     

In response to the UK Statistics Authority Inclusive Data Consultation we are attaching our recent response to the draft guidance on collecting data on sex and gender published by Scotland’s Chief Statistician in December 2020, which can be accessed here:

More invisible women? MBM response to the Chief Statistician’s draft guidance on collecting data on sex and gender

Whilst some of the observations are specific to Mr Halliday’s report, the key arguments we present are applicable to inclusive data collection more broadly. Our main concern is the loss of data on the protected characteristic of sex, and its replacement with data on self-defined gender identity.

Biological sex is well-established to be a key influence on a person’s experiences and outcomes, and one of the most important variables for the purposes of policy, planning, and research. This view is supported by decades of robust research evidence and analysis, which has examined the relationship between being born physically one sex or the other, and a person’s physical, social, economic, and political experiences and outcomes from birth onwards.

Existing research has not only demonstrated substantial differences related to sex in outcomes and experiences across multiple contexts, it has also sought to provide explanations for these differences, based on studying the potential mechanisms. Researchers have examined, among other things, how different social and educational responses to girls and boys from birth onwards may influence future behaviours and choices; employer reluctance to employ and promote women who are perceived as a ‘pregnancy risk’; the effect of going through a male puberty on the body, for factors such as strength and height, affecting differences in areas such as sporting performance. The precise link between socialisation and social perceptions and expectations based on sex, and sex itself, is often contested: but both come back to the same point, the sex a person has.

The loss of data on sex and its replacement with data on self-defined gender identity is already apparent across multiple data collection exercises, including the Scottish Household Survey, and in the fields of health, higher education, and criminal justice data. In relation to the census, our research has shown how the introduction of guidance based on ‘self-identified’ gender identity was shaped by reference to a limited group of interests that excluded those of women.

This shift has significant implications for the accuracy and reliability of statistics, in any category where there are established differences by sex. For example, the inclusion of a very small number of biological males who identify as female in criminal justice data could easily skew female offending patterns. Indeed, given that police forces no longer record data on biological sex, we think that official data on female convictions for crime types for which the prevalence is low can no longer be viewed as reliable, particularly as trend data. The shift also has detrimental implications for equality monitoring, and the ability of public organisations to gather information on the protected characteristic of sex.   

In our response to the Chief Statistician, we note that the draft guidance fails to consider or account for changes in the size and demographic distribution of the trans population, and the implications of this for data reliability at a subgroup analysis. The same is also true of the methodological paper presented by the ONS to the Methodology Assurance Review Panel (MARP), in relation to its proposed approach to the sex question guidance (our review of the ONS paper can be accessed here).  

In recent years, those advocating for the replacement of sex with gender identity in data collection has argued that to ask a person’s sex may be an invasion of privacy, and breach Article 8 of the Human Rights Act (see further section 1.5 in our response to Mr Halliday). This argument was rejected in Fair Play For Women v The Office For National Statistics, in which Judge Swift stated that asking a person to report the sex on their birth certificate in the census was proportionate and did not interfere with privacy rights. It is also striking that the same privacy considerations are not generally extended to other intimate questions that pertain to a person’s biology, for example questions about age, disability, or health, which people might reasonably feel to be more intrusive than their sex

The UK Statistics Authority’s five-year strategy states that statistics should ‘reflect the experiences of everyone in our society so that everyone counts, and is counted, and no one is forgotten’ (2020: 13). As noted above, and detailed further in our response to Mr Halliday, it is clear that there are already significant data gaps in relation to the protected characteristic of sex as a result of data collection practices that blur sex and self-identified gender identity, and make it impossible to disentangle the two. We would suggest that these gaps have arisen in part because the interests of women and expert data users have not been adequately considered in decision-making processes.

Without urgent remedial action we think that these gaps are likely to increase, with further detrimental implications for planning, policy, and research, as well as our ability to understand and redress unequal outcomes on the basis of sex.

Yours sincerely,

Dr Kath Murray

Lucy Hunter Blackburn

Lisa Mackenzie      


[1] Murray and Hunter Blackburn (2019) Losing sight of women’s rights: the unregulated introduction of gender self-identification as a case study of policy capture in Scotland Scottish Affairs, 28(3)

[2] Our parliamentary evidence and correspondence, briefings, blogs and media commentary can be accessed here.

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