I once did an online IQ test and then got interrupted by someone else after five minutes and I quit the test, my score was apparently 88. I don't trust online IQ tests, I only did it because someone annoyed me into taking it and someone annoyed me out of taking it.
I honestly think IQ scores primarily measure how much you want to score well on an IQ test. You can improve your scores by 10 points according to scientific papers just by being more motivated and not quitting, not being distracted and so on.
I don't trust online IQ tests because the scores I get on them range from 110ish to 180ish and despite my robust self-esteem I don't see a score of 160+ as especially credible. :P
Real (ie. official medical) IQ scores seem to be heavily skewed around age and speed. So the same performance would get you a super high score in a 5-year-old and a mediocre score in a 10-year-old, which is weird because the questions are explicitly trying not to test language/knowledge type stuff that would change a lot between those ages. And the same answers would get a far higher score if you bashed them out in 15 minutes than if you took 2 hours on them. I haven't gone back to re-examine it but I remember thinking that you were way better off smashing through the questions as fast as possible and getting a few right than carefully considering the questions... which is an odd way to define intelligence.
I honestly think IQ scores primarily measure how much you want to score well on an IQ test. You can improve your scores by 10 points according to scientific papers just by being more motivated and not quitting, not being distracted and so on.