By Lucy Hunter Blackburn, on behalf of MurrayBlackburnMackenzie, Edinburgh

EVERY 10 years, the Government conducts a national census, to establish basic facts about the population: how many of us there are, and what characteristics we have. Because it asks everyone, the census allows analysis at a level of detail that sample surveys cannot. It is used by a huge number of organisations to inform their strategic planning and to understand how Scotland works now. It is also a major investment: the 2011 census cost nearly £64 million.

In 2021, the Scottish Government plans to gather data for the first time on sexual orientation and on the transgender population, using voluntary questions. This is not controversial: the census is the ideal way to gather information on small populations we know very little about. Doing so voluntarily reflects the sensitivity of the information.

Last week, in a report on the first stage of legislation required ahead of 2021, the Culture, Tourism, Europe and External Affairs Committee recommended that the census continues to ask about sex consistent with the way it is defined for all of us in law, with two possible responses (female and male), as it has done since 1801.

Against a backdrop of broader societal change, the decision has prompted criticism that people who do not identify as either a woman or a man will not feel able to answer accurately, if the sex question has only two possible answers. Sex may be a legal fact for everyone, but not everyone regards it as personally relevant. For this reason, it is argued, the sex question should be replaced by one which allows responses other than male or female: in effect, it would become a question conflating sex and gender identity.

The committee’s position is that the census should keep the ideas of sex and gender identity distinct, and gather data separately on both. I was among the witnesses to the committee who agreed that this approach would make the most of the opportunity in 2021 to improve our understanding of the whole population.

The central issue here is the purpose of the census, which is to provide robust data for public planning, policy-making and research. It is clear that user needs include data on sex, which is used for instance, to inform the allocation of resources to health boards, or to examine how far the interaction of sex, education and employment has changed over time.

Also relevant is the Equality Act 2010, the main piece of legislation that protects people against discrimination or unfair treatment. Sex (in two categories) is one of nine “protected characteristics” under the Act. The Act also requires public authorities to eliminate unlawful discrimination and advance equality of opportunity based specifically on each of the protected characteristics. The Office for National Statistics position for the 2021 Census for England and Wales is that a binary sex question is needed for public bodies to uphold their duties under the Equality Act 2010.

If the question on “sex” becomes in practice a question on gender identity, we cannot know how this would affect the data. Small differences at the level of the whole population could become significant for particular sub-groups, perhaps most obviously by age. Losing reliable data on sex will make it harder to tell how well hard-won protections set out in the Equality Act are being upheld across the population.

The census is a once-in-a-decade opportunity: getting the data right matters. Irrespective of wider societal change, sex-based discrimination remains stubbornly commonplace. As such, the approach recommended by the committee, which purposefully avoids conflating sex and gender identity, is both pragmatic and welcome.