Many high IQ societies accept scores from the GRE, LSAT and other graduate school admission tests. For example Mensa, which requires you to be smarter than 98% of Americans (for your age group), will accept you if your LSAT score is higher than 95% of LSAT takers. But how does Mensa know that being smarter than 95% of LSAT takers is equivalent to being smarter than 98% of Americans? I don’t think they do, they just know that since the LSAT population is smarter, one’s percentile among the LSAT population underestimates one’s percentile among Americans, but conservatively assumed the underestimation is small to avoid admitting unqualified people. So to Mensa’s credit, they probably erred on the side of maintaining standards (instead of profits) and rejected LSAT scores below the 95th percentile, even though many of those people likely qualified.

I can’t find much data on the IQ distribution of LSAT takers, but assuming they’re roughly equivalent to GRE takers (both tests are for admission to post-bachelor degree schooling), then the following is relevant:

In a sample of people who took both the GRE and the SAT (circa 1990), the mean GRE and SAT verbal was 510.1 (SD = 107.7) and 518 (SD of 104.7) respectively. Rare norming studies show that if all Americans took the SAT circa 1983, the mean and standard deviation (SD) would have been 376 and 102 respectively, which means that on an IQ scale (mean 100; SD 15) they had a mean verbal IQ of 121 (SD 15.4).

Now assuming the same for the LSAT, the 95th percentile (+1.66 SD) equates to an IQ of:

1.66(15.4) + 121 = 26 + 121 = 147

So when Mensa was screening out anyone with LSAT derived IQ scores below 130, they were also screening out everyone with IQs below 147!