People's IQs increase when their level of education increases. That's one reason I have little faith in IQ tests.Back in the late 80s I bought an IQ test at the mall book store. I did well, but I question the validity of such a test because it was for sale. A test which is bias to high scores may sell better than one that is bias to low scores. If I had scored "less than average" I would be less likely to give the test word of mouth advertisement than if I score well on the test. In other words, there is a bragging factor in marketing the test.
Especially an education in critical thinking.
