Take [for example] the Myers-Briggs Type Indicator (MBTI), the world’s most popular psychometric test, which is based on Jung’s theory of personality types. Th

Take [for example] the Myers-Briggs Type Indicator (MBTI), the world’s most popular psychometric test, which is based on Jung’s theory of personality types. The MBTI is based very loosely on Jung's theory -- to the point that it's not at all clear that Jung himself would have endorsed it. Jung described eight types, not 16. Some years ago I read the descriptions of the eight types in Jung's Psychological Types and compared them with the nine types of the Enneagram. Indeed, Jung's descriptions matched up very well with eight of the Enneagram types. (He missed the Three.) The MBTI, by comparison, is a mess. It's hard to say, in many cases, how the MBTI types match up against either Jung's or the Enneagram.