Hi Vicki, Thanks for all you comments. I can see that you're heavily invested in MBTI, so I won't try to change your mind with my comments. I'd just like to point out a few things. The first problem with MBTI is that the questions are extremely vague and can often be answered with "it depends". Jung's theories are meant to be used as part of a dialogue between patient and doctor, so that these can be fully explored. MBTI relegates these ambiguities to simple yes/no responses. A question like "You like to be engaged in an active and fast-paced job" really has a host of answers. "It depends on the money." "What is the rest of the team like?" "Do I have a lot going on in my personal life?" You say that most people's MBTI don't change over time. Repeated studies have shown that they do. For example, the paper “Test-Retest Reliabilities of the Myers-Briggs Type Indicator as a Function of Mood Changes.” Research in Psychological Type, Vol. 2, No. 1 (1979), pp. 67-72, by Howes, R. J. and T. G. Carskadon. There's no evidence to suggest that the inventors had lots of data when they were creating the system. You're right that there has been lots more data added - unfortunately, when assessed it always seems to come up short. See Druckman, D. and R. A. Bjork, Eds. In the Mind’s Eye: Enhancing Human Performance. Washington, DC: National Academy Press, 1991 (a study undertaken by the US Army). I quite agree that you don't need a CompSci degree to do programming - but if you don't understand O(n), regression, and sorting algorithms - you're likely to make some very basic mistakes. The MBTI inventors had no training in psychology or statistics - and that shows in their work. We both agree that MBTI is often misused - especially by people with little training in it. Where we differ is that I don't believe that someone who has paid to become MBTI Qualified knows any much about human psychology than an astrologer. If, as you say, MBTI types are fixed, then they are presumably fixed at birth. Much like star signs. Thanks Terence