Proposals to test the census sex question guidance miss the point

As part of its preparation for the 2021 Scotland census, National Records of Scotland (NRS) are planning to commission testing which looks at the effect of offering different forms of accompanying guidance for the sex question. The sex question itself will be binary, and simply ask if a person is male or female.

The guidance is important because this has the effect of determining the meaning of the sex question. Currently, NRS propose to publish guidance which will indicate that sex has no definition beyond the respondent’s self-assessment (self-identified sex). We understand that the Office for National Statistics (ONS) are proposing similar guidance for the England and Wales census. However, recognising that concerns have been raised about self-identification as a basis for answering the sex question, the guidance will be subject to further testing over the coming months.

Proposed approach to testing: self-identified sex versus legal sex

Testing will compare the results of the sex question having accompanying guidance that will indicate that sex has no definition beyond the respondent’s self-assessment; with it having accompanying guidance that directs people to answer in terms of their legal sex, as recorded on a person’s current birth certificate or their Gender Recognition Certificate (which applies to around 400 to 500 adults aged 18 years or over in Scotland). Both sets of guidance will be tested in conjunction with the trans identity question (which is explicitly designed to collect data on gender identity), and the sexual orientation question.

Testing will look at any variation in response rates to the question between the two approaches, if and how responses in each case interact with the voluntary transgender and sexual orientation questions, and data quality.

Testing will be quantitative only, with a main sample of around 5,000 respondents, and a small booster sample of people who have been identified through groups who advocate for gender self-declaration or who have otherwise made themselves known to NRS as being transgender.

How will people access the guidance to the sex question in the 2021 census?

The 2021 census will be web-based, and a link to the guidance will be made available on the online questionnaire. This format means that the accompanying guidance will be both prominent and accessible.

This level of accessibility is much higher than the 2011 census. Online guidance on the sex question was provided for the first time in 2011, which stated that transgender or transsexual people could select the option for how they identify, irrespective of the details on their birth certificate. NRS advise that only 20% of households responded online in 2011, and even for those respondents, the guidance was not linked to the online questionnaire. This meant that respondents, whether on paper or online, needed to actively seek out the online guidance. There is no record or assessment of how far the 2011 guidance was used by respondents, or how this influenced responses. The difference in approach between the two censuses however makes it a reasonable assumption that any guidance used in 2021 will be more widely seen than guidance published in 2011.

What is the problem with a self-identified sex question?

We are concerned that the NRS approach to testing does not address any of the key concerns in respect of a self-identified approach to the sex question.

These are: the fundamental redefinition of male and female within the context of Scotland’s oldest and most important population survey; the precedent this sets for other surveys and more widely; and the departure from the legal definition of sex in the Equality Act 2010, which carries implications for equalities monitoring (see further here).

From a data perspective, a question which solicits responses based on self-identification is not based on clear criteria and instead conflates two separate demographic characteristics, namely sex and gender identity. In other words, it is not a sex question. This carries significant implications for data quality. It means that for an unknown (and unknowable) number of people, the census will collect a different type of data to sex. With no reliable estimate for the moment as to the size of the trans population, it cannot be safely assumed that this will have no impact on the value of the census as a source of reliable population-wide information about sex, and how it relates to other policy areas, such as health, education and employment. From the limited evidence we have, the risk to data quality is likely to be higher among some sub-groups, particularly young people.

Giving evidence at Stage One of the Census Bill, Professor of Quantitative Criminology Susan McVie stated:

I think that the General Register Office for Scotland got it wrong when it redesigned the census in 2011 and conflated sex and gender identity into one question. We are now trying to disentangle those things. Arguably, the measure of sex in the 2011 census data is not accurate. (McVie, 13 December 2018. Col. 4)

A sex question soliciting answers based on self-identification is not consistent with the Culture, Tourism, Europe and External Affairs Committee (CTEEA) recommendation in the Stage One report on the Bill:

The Committee has received considerable evidence that there was a lack of clarity and awareness regarding the existence of online guidance concerning the self-identification approach adopted in 2011. The Committee considers that there must be absolute clarity with regard to the approach that is adopted in 2021, taking into account the census’s primary purpose of robust data-gathering and the Scottish Government’s duty to act in accordance with the Equality Act 2010, in which sex is a protected characteristic. The Committee recommends that there is a pro-active information campaign to support the approach adopted which must involve all interested parties who which have expressed views on this issue. (CTEEA, 2019: para. 8. Our emphasis)

Why are NRS testing a self-identified approach to the sex question?

It is unclear why NRS are proceeding to test guidance for the sex question soliciting responses based on self-identification.

A recent letter from Cabinet Secretary for Culture, Tourism and External Affairs Fiona Hyslop MSP stated that this would maintain continuity with the 2011 census [i]. However, the guidance published in 2011 was not only much less easily available than any guidance will be in 2021, it was also an outlier. No guidance related to sex was published in the previous censuses between 1801 and 2001.

The primary purpose of the census is to provide information to develop policies, plan and run public services, and allocate funding. The data collected in the census should reflect user needs, be of high quality and serve the public good. We have not however, seen any robust arguments to support the position that a sex question soliciting answers based on self-identification would be consistent with these aims and principles. NRS have acknowledged that they have not been asked to follow this approach by any data users .

How should testing proceed?

We do not believe there is any value in testing the effect of offering guidance based on self-identified sex, because soliciting responses on this basis is not consistent with the primary purpose of the census. It is therefore unclear how further testing could contribute to the decision-making process.

We think that the sex question should, as it unequivocally states, collect data on sex, and not data on gender identity. Any further testing should therefore have as its clear and sole purpose ascertaining the best way to do this. NRS may wish to look at how people are likely to understand and respond to the sex question, and the value of providing additional guidance based on legal sex. For example, testing might consider the extent to which respondents are likely to use such additional guidance, and whether this is likely to affect how a person responds.  Data on gender identity, where this differs from a person’s legal sex should be clearly collected as a category in its own right, using the separate voluntary transgender question.

The census is a once-in-a-decade opportunity to survey the population. It is a complex and expensive programme (£64 million in 2011) and getting the data right matters. As Compton, Wilson and French state:

The planning and execution of the decennial population census is a vast and complex undertaking often described as the largest peacetime operation carried out in the UK. It is certainly the largest statistical exercise, aiming to collect socio-demographic information from every individual and household in the four home nations.

We believe that the Scottish Government should continue collecting reliable data on sex until there is compelling evidence that it is no longer needed, and that NRS should revise its testing plans accordingly.


[i] 2011 online guidance
In the 2011 census, both the ONS and NRS introduced online guidance advising that respondents could answer the sex question based on self-identity. The Scottish Government has interpreted the 2011 guidance as setting as a precedent for the 2021 census. However, it should be noted that the 2011 census had no other option for people to record their gender identity, separate to sex, which resulted in this fudged approach.

The introduction of a separate transgender status question in the 2021 census to record gender identity means that the 2011 precedent is no longer relevant. Nonetheless, it appears that the Scottish Government is continuing to view the previous fudge as a permanent concession that respondents should never declare what is on their birth certificate. It has not however, made clear why this concession is justified, nor how it reached its conclusion.