If the things are to do with anything related to sex, ie the results are to do with "gender" (sex) pay gap, differences in accessing services, experience of crime, anything, then they need to ask sex.
Ditto if they want to know if trans people have certain experiences or are not engaging with services or whatever then the question needs to ask if the person is trans.
All of this is interesting. "Identify as" means anything, you can say whatever you like, it renders everything meaningless.
People are male or female, and this impacts their experience massively all over the world.
If they need to know gender then they need two questions. 1. male / female / intersex. 2. gender list of the top 10 or whatever. And it can't say "male female man woman" as they relate to sex. Gender is masculine / feminine etc.
That's not how it goes now. I feel really quite sad at the fact there are no words left in general accepted discourse in the UK to talk about e.g. girls and mean "female children, you know the cunty ones".