I know how this is going to sound, but I'm genuinely curious: how do they measure whether the evaluations are gender biased, or whether the quality of the instruction is not equally distributed between the genders?

Before I get a bunch of hate and downvotes, I'm not suggesting that female teachers get lower evaluation scores because they're not as good on average as their male counterparts. But I assume that researchers can show why that's not the underlying source of the difference in ratings, since that would be an obvious objection to these findings. Just curious how they separate that out, that's all.

EDIT: nevermind, this was just laziness on my part. Here's the study, and it's actually not that hard to understand: https://www.scienceopen.com/document_file/25ff22be-8a1b-4c97...

TLDR: In one experiment, they randomly assigned students to a TA and compared how well the students did in the class to determine whether the instructors were of comparable quality. In another experiment they secretly switched the TA identities in an online course so the students who had the female TA thought they had the male TA, and vice versa. Very nice.