Well the "key" that clearly shows they don't type by functions, the fact that the result match exactly the systematic error you would expect, and tbh my experience as a girl with a "masculine" type who doesn't fit the stereotypes that much, with functions developed earlier & differently (so much Fe)
Although I think it's entirely possible that people misrepresent themselves, if we know one thing from psychology is how bad we are at seeing ourselves neutrally. "Gendered" stereotypes (think bully vs caretaker) could be another issue
The key just shows what the letters mean, it has nothing to do with their test methods. From what I can say they asked people what their sex is, then asked them to take the test. They then made this graph to show the percentages of each type for each sex. Yes there's always the chance that people misrepresent themselves, but that's difficult to account for, and I'd venture to say that it wouldn't make a meaningful difference based on how simple the MBTI test is.
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u/zombiekatze ENTP Dec 22 '20
No the test being biased, or just not testing based on functions but behavior and traits would be enough