The difficulty I see with MBTI is that the categories were decided in advance, whereas they should be determined based on the data. In other words, MBTI treats

The difficulty I see with MBTI is that the categories were decided in advance, whereas they should be determined based on the data. In other words, MBTI treats human personality as a classification problem (which of these categories do you belong to?) where it should be treated as a clustering problem (which categories even exist?) I'd love to do some data mining on a large MBTI test database. Better yet, a large database of people's responses to various personality-oriented questions, MBTI or not.