It's not a poor methodology if you are simply measuring starting salaries only, or if salaries never increase. But it is reckless to make a bold declaration that "there is no gender gap in tech salaries" based on this data.

I don't think it's hard for people to imagine that there is less variance in starting salaries. Reading into this data and thinking it applies to anything beyond that is a guess and should be treated as such with that guess being tested in future studies.

Even if you demonstrate there is no wage discrimination over the course of people's careers, it doesn't account for the huge gender gap in the industry.