Trans identity becomes an issue in Britain's census
(Because data will be mostly collected online, and because of the guidance of the form - many will 'self-id' rather than report what is on their official documents. This means many will use a gender identity that has not been officially changed)
Data on sex are used to predict fertility and life expectancy, and to plan all sorts of public services, including maternity provision, school places, housing, health and old-age care. Many diseases are more severe for one sex than the other—men are more likely to die from covid-19, for example, but women spend more years in poor health at the end of their lives. Academics use historic census data on sex to study everything from social mobility to correlates of health, and how they change over time.
“Sex is a massive predictor of every dimension of social life,” says Alice Sullivan, a social scientist at University College London. “There are huge gaps between the sexes when it comes to pay, education, crime, religion and social attitudes.” When concerns about the guidance first emerged in 2019, she organised an open letter of protest to the ONS by 80 eminent users of census data.
Some women’s groups also oppose the guidance on the ground that any blurring of the meaning of sex is bound to harm women. The only way to tell whether sex discrimination is happening, they argue, is to have robust numbers. And the guidance may also undermine the attempt in the census to find out just how many trans people there are in Britain. A voluntary question asks whether each adult respondent’s self-declared gender identity differs from their sex. If trans people respond to the sex question with their self-identified sex, they may then record their gender identity as matching their sex, thus leading them to be undercounted.
https://www.economist.com/britain/2021/02/16/trans-identity-becomes-an-issue-in-britains-census
Article also reports that some trans-activists are happy with self-id and some social scientists unhappy (since it will impact data)
ETA:
Several women’s groups are seeking an emergency judicial review, arguing that the ONS is neglecting its legal responsibility to collect robust data about protected characteristics.
