IQ tests are also arbitrarily calibrated to have their own conclusions built into the system. This disqualifies them as science straight away.
e.g. there are some questions that men tend to do better on, and some questions that women tend to do better on. Regardless of why this is the case, it's a tool that is used by IQ test designers to engineer-in gender neutrality into IQ tests. But that's entirely circular logic when you think about it. The assumption is that IQ is equally held by both genders, the tests are designed to produce results that adhere to that assumption, then the test results are used to make claims about equality of IQ. Which other "science" could get away with such a blatant fabrication of research results, other than the "science" of "psychometry"?
This whole debacle means you should ignore any study that says men or women have higher IQ. It's completely meaningless, and it's subject to arbitrary swings back once they recalibrate the latest IQ tests. IQ test results rise with higher educational opportunities. Men were a little ahead before (back before women had many educational opportunities), but recently women have edged ahead, to great media fanfare. The most likely actual reason isn't "women are getting smarter" in any genetic sense, it's that women worldwide have rising educational opportunities, and this has caused their scores to rise against the older tests (which were calibrated to be gender-neutral at a time when women had less educational opportunities).
There's also the high amount of correlation between the types of questions that are on traditional IQ tests, and the typical middle-class Anglo-Saxon school curriculum of 100 years ago. Knowing obscure English vocabulary and having memorized your times tables was the definition of "IQ". A better name for the test would be the "middle class educational attainment test", and every test since then has been calibrated against the existing tests. Basically an IQ test is purely judged by it's correlation with earlier tests, so if the earlier tests were conceptually flawed, it's hard to see how later "improved" tests are actually any better. I'm pretty sure you could load a test with working-class concepts and questions and make working-class people look much more intelligent, but such a test would be rejected outright because it "doesn't correlate" with the pre-existing "intelligence" tests.
So we can say without a doubt that the IQ test is a good indicator at being good at the things on the IQ test. But it's much more tenuous to say it predicts anything else. Notice how they hardly use IQ tests at all anymore? They used to be widely used in employee selection. Now, it's mainly online quizzes, Mensa, and used to plead mental incompetence so you can avoid Death Row. The reason for the almost wholesale abandonment of IQ testing as a tool by business and government is that they don't predict anything useful about your level of performance for just about any task possible.