I have heard that IQ measurements correlate very well with general success in society. Peterson says they correlate better than any other measurement in human Psychology. (Paraphrasing and I can't validate it)

Peterson also says that it doesn't matter which questions you use. People with hi scores on one test will typically have high scores on the other tests.

It seems to be a hard thing for intelligent creatures to hear:

There are some smarter that you and some less smart and you are most likely in the middle range somewhere.