Mensa uses +2 sigma as the cutoff for membership. Above that, the other societies use +3 sigma (Triple nine society) and +4 sigma (Prometheus society) and their entry tests criteria are very strict, so you may have to sit a different test to achieve entry. The problem is that tests for these purposes take a lot of effort and time to design and validate. The internet enables questions and answers to be leaked, so almost all of the applicable tests have been compromised, so membership of these societies have fallen drastically.
The Puttyverse looks fantastic. Amongst mature adults, I’ve found that it’s not so much raw IQ which makes an individual interesting and worth listening to and learning from, but how much expertise they’ve gained in their chosen field(s) of interest.
