Maybe the reason MENSA's tests are reliable is that not many people are interested in joining MENSA - I am not denying that MENSA can be of interest, but its ad

Maybe the reason MENSA's tests are reliable is that not many people are interested in joining MENSA - I am not denying that MENSA can be of interest, but its admittance would not be worth preparing IQ tests like crazy. On the other hand, if IQ tests were used for admissions in prestigious universities, you can bet some students will train specifically for IQ tests.