GUIDANCE accompanying the next census should ask Scots to declare whether they are male or female based on how they self-identify, rather than their legal sex, census authorities have recommended.

National Records of Scotland (NRS) outlined the proposal despite 80 academics and statisticians raising concerns that this will conflate sex and gender, and impact on the accuracy of the data.

It follows controversy over online guidance published for the 2011 census, which advised transgender people to respond to the sex question based on how they self-identify, irrespective of the details on their birth certificate or whether they have a Gender Recognition Certificate.

Authorities also considered introducing a third option to the sex question in 2021, allowing individuals to define themselves as other than male or female, but this was scrapped.

Dr Kath Murray, a criminologist and member of the MurrayBlackburnMackenzie policy analysis collective, said officials had ignored the advice of 80 senior academics.

She said: “The proposed question and guidance carries risks in terms of data reliability and consistency over time, as well as equalities monitoring.

“It is particularly concerning that officials have ignored the advice of 80 of the UK’s most eminent academics, working in relevant disciplines, who have called on the census authorities ‘to retain the integrity of the category of sex, and not to conflate this with gender identity’”.

Alice Sullivan, Professor of Sociology at University College London, also expressed concern on social media. 

She wrote: “It is deeply worrying that the views of the scientific community have not been taken on board.”

The census has collected data on sex since 1801, which experts argue is of vital importance to the planning and delivery of public services.

The letter from 80 academics, which was sent to the directors of the three UK census authorities, as well as Boris Johnson and Nicola Sturgeon, said the online guidance issued on the sex question in 2011 should not be seen as a precedent.

It added: “The introduction of guidance in 2011 was not subjected to a full consultation with data users, nor was an equality impact assessment undertaken.”

It raises concerns that the shift to a “digital-first” census in 2021 “means that any proposed guidance will be much more visible and accessible, compared to the 2011 census (which was predominantly paper based, with separate online guidance)”.

However, the signatories welcome a new, voluntary question on gender identity in the 2021 census in England, Wales, and Scotland.

A previous letter signed by 50 academics and data experts called for the 2011 census guidance to remain in place amid fears trans rights were at risk of being eroded.

The NRS said a study showed most people will not consider guidance prior to answering the sex question.

Its report states: “The basis on which they answer is therefore not explicitly defined and therefore NRS take the position that self-identification captures the reality of how people complete this census question.”

It said research indicated three times as many trans and non-binary Scots – who identify as neither male nor female – would be willing to answer a sex question with self-identification guidance than with legal sex guidance.

The report added: “A binary sex question with self-identification guidance therefore supports participation for all people with the census and clarifies to data providers and data users the basis of the question.”

Proposed guidance to accompany the sex question in the 2021 census reads: “If you are transgender the answer you give can be different from what is on your birth certificate. You don’t need a Gender Recognition Certificate.”

A NRS spokeswoman said the final decisions on Scotland’s 2021 census questions would be made by Holyrood next year.