There might be a selection bias with a sample based around your associates though. Birds of the same feather flock together? I found this site which gives some estimates for the USA: http://www.myersbriggs.org/my-mbti-...ti-results/how-frequent-is-my-type.htm?bhcp=1 3-5% for INTPs, covering a period from 1972-2002. As for the matter of extroverts being more than introverts, the statistics on the site I linked point to the answer being "Even split", roughly favoring Introverts a little. Extroverts are expected to be 45-53%, while Introverts are 47-55%. While INTP types are supposedly rare, other MBTI personality types that are Introvert are relatively common (i.e. ISTJs at 11-14% and ISFJs 9-14%.) Edit: As for my results, I consistently get INTP across MBTI tests run by different sites.