IQ is really tricky to judge objectively. There was a study done with Asian women. They first gave them a test as a base-line, then they reminded them of feminine stereotypes and gave them another test which showed lower results than the base-line, then they reminded them of their Asian stereotypes and gave them another test which showed higher results than the base-line. You could probably argue that this is just yet another example of the left trying to discredit any genetic or gender based link with IQ, but the results were within the standard deviation for placebos effects in a population with average hypnotic suggestibility.
This isn't to say "IQ is all in our head" or anything like that, rather most aspects of consciousness have some play to them. Things like genetics, developmental nutrition, gender, etc are all likely more important than ones own conscious perspective in the grand scheme of things though, leaving aside self-sabotaging mind-sets, simply because they are more permanent.
It is also very difficult to get a good read on what intelligence actually is. The IQ system focuses mainly on pattern recognition in various forms. Which is fine, and I'm not one to harp on about EQ and things like "musical intelligence", but I still do think that the ways that IQ tests are written aren't that great simply because they aim at measuring an analytical rather than synthetic form of cognition.
There's also how even "officially sanctioned" IQ tests are not all created equal, and as well what state of mind the test taker is in (setting aside the placebo effect). I've scored anywhere from 129 at the lowest to "155<" (the test maxed out at 155) at the highest, using different IQ tests and different states of mind. When I scored the lowest, I was suffering from fatigue syndrome, I had a semi-severe cold with a light fever, and there was a bunch of stuff going on in my personal life making it difficult for me to concentrate. When I scored "155<" I had none of those issues, but that particular test didn't take into account completion time, and that's always been my worst category on the tests that
do take it into account. I've even taken the
exact same IQ test at different times and gotten significantly different results, so it's not quite so simple as to say that different tests aren't created equal, either.
So, yeah... IQ tests are definitely not the end-all, be-all of intelligence.
And just to throw in a semi-serious appeal to authority, there's always Stephen Hawking's famous quote from when he was asked about what his IQ was: "I have no idea. People who boast about their IQ are losers."
Buuut... if you want to talk about using the same IQ test and comparing results across groups, the perhaps most poignant difference (at least that I know of) is the difference between men and women: while the
average IQ differs by less than 0.5 points, the IQ
variance is incredibly different between them. On the statistical level, men display the standard bell curve, whereas women instead tend to cluster around the mean. In other words, despite the average being nearly identical, there are a lot more male geniuses than there are female geniuses. But, on the flip side, there are also a lot more male
idiots than there are female idiots.
Even setting aside male and female career choices/preferences, that IQ variance probably goes a long way to explain why more men go into STEM fields. For every woman who's smart enough to qualify, you've got not one, not two, but
several men who are also smart enough to do so. In other words, even if every single woman in the world who had the potential for it went into STEM, they would
still be significantly outnumbered by men (Well, barring political action coupled with a limited number of available STEM positions, anyway).
Of course, statistics don't mean a damn thing on the individual level, which is why you still need to evaluate every person individually in order to get the best possible results. And evaluating people individually rather than as a group is something that certain sociopolitical movements absolutely despise, so...