Our new blog argues that the UK is losing robust data on sex and the framing of the sex question in the 2021 census is set to make the situation worse.
murrayblackburnmackenzie.org/2020/06/20/dom…
murrayblackburnmackenzie.org/2020/06/20/dom…
Already some data collection exercises have ceased collecting data on sex & are instead replacing it with data on self-declared gender identity. A recent YouGov survey asked respondents to identify themselves on the gender spectrum but apparently did not ask for respondents' sex. 
In response to a complaint about the question format, YouGov subsequently explained that it had implemented the change to reflect the forthcoming UK census, and that other market research companies were planning to do the same.
In 2018 the Scottish Government changed the binary sex question in the Scottish Household Survey, to a question that asked respondents to describe their gender identity, stating that this was ‘in line with similar changes being made to other major surveys in Scotland’.
The widely downloaded KCL COVID-19 Tracker App, developed to better understand the symptoms and spread of COVID-19, quickly changed its original male/female sex at birth question, to ask people about their sex ‘assigned at birth’ and whether they are male, female or “intersex”.
A survey by the London School of Hygiene and Tropical Medicine considering how people were coping with the Covid-19 pandemic and how information about the disease was being shared in communities listed five potential responses to the question ‘What is your gender?’.
This shift in data collection practices has come about principally as a result of lobbying by some LGBT groups. For example the Stonewall/Scottish Trans Alliance ‘Getting Equalities Monitoring Right’ guide explicitly advises organisations against collecting data on sex:
In framing the sex question in the 2021 census in terms of self-declared gender identity the UK census authorities are clearly signalling that they no longer view sex as a key determinant from birth onwards of a vast range of outcomes relevant to the formulation of public policy.
The UK census’ flagship status also means that the census authorities are giving implicit licence to other data collection surveys to follow suit, and that the elision of sex and gender identity is even more likely to be replicated elsewhere.
As a result, the UK is now at a serious risk of losing the capacity to gather data that, for decades, has provided the building blocks for policy-makers and researchers to monitor and tackle discrimination based on sex.
