A: It’s not really possible to get a valid IQ test online. They have to be administered and scored by humans because there are a lot of judgment calls involved, and a multiple-choice format simply doesn’t lend itself to that kind of thing.
I’m from the US, and I’ve studied IQ a lot because I’m fascinated with statistics and with tests and measures (I’ve got a psychology degree, plus I’m autistic, which makes a very obsessive type of researcher!). And take it from me: People in the US overvalue IQ. It means much less than it seems, and says less about intelligence than people think it does.
IQ tests break down whenever someone who's atypical in some way gets tested. If your neurology is unusual, your communication style is unusual, even your culture is different, IQ tests start to say less and less until in the end, they say nothing.
The tests aren't utterly useless. Generally, we can tell if somebody’s outright gifted or outright learning-disabled from an IQ test, if it’s administered carefully on a good day with no cultural barriers, but the precise numbers themselves are really very deceptive. The idea that somebody with an IQ of 112 is smarter than someone with an IQ of 110 is just ridiculous. It just isn’t that precise. Only once you get to two or more standard deviations worth of difference do I feel that the differences are worth making a note of—and since the IQ test has a standard deviation of 15 or 16, that’s a big difference, the difference between average and gifted or average and intellectually disabled.
That’s not so surprising, considering that the original IQ tests were meant to identify students who needed extra help. They still fulfill that function reasonably well. But they were never meant to rank people by intelligence.
If face-to-face IQ tests are of so little worth, fail so often and say so little about us, you really can’t expect online IQ tests to be worth much at all.
Instead of worrying about IQs, we should focus on what we’re good at doing, what we’ve worked hard on, what we enjoy learning. That’s what really matters.
To those who want to learn more about IQ, I recommend the book "The Mismeasure of Man", by Stephen Jay Gould. It’s old—written in 1981—but it addresses a lot of the issues with testing intelligence and cognition, and explains why it’s hard to do and why it's much less applicable to daily life than you’d think.