INFP? ISTJ? You’ve probably taken a personality test at some point. But here’s the bad news: even the most popular tests, such as Myers-Briggs (MBTI), are not to be trusted. Retake a Myers-Briggs test after just a five week gap and there is a 50% chance you’ll be put into a different personality category. In this article at Fortune Magazine, I reveal the shocking truth about personality tests.