Myers-Briggs Type Indicator is silly
I've been reading some online stuff and have found this excellent page on Forer, a psychologist from the 1st half of the 1900s.

He gave his students a personality test and ignored the results and gave them all the following paragraph as a description of them

You have a need for other people to like and admire you, and yet you tend to be critical of yourself. While you have some personality weaknesses you are generally able to compensate for them. You have considerable unused capacity that you have not turned to your advantage. Disciplined and self-controlled on the outside, you tend to be worrisome and insecure on the inside. At times you have serious doubts as to whether you have made the right decision or done the right thing. You prefer a certain amount of change and variety and become dissatisfied when hemmed in by restrictions and limitations. You also pride yourself as an independent thinker; and do not accept others' statements without satisfactory proof. But you have found it unwise to be too frank in revealing yourself to others. At times you are extroverted, affable, and sociable, while at other times you are introverted, wary, and reserved. Some of your aspirations tend to be rather unrealistic.

He then got them to rate the accuracy of the description from 0 to 5. 5 being excellent and 4 being good. The class average was 4.26 since then the test has been done many times and the average is 4.2 (please ignore the fact that with a discrete scale such as 1,2,3,4,5 you cannot validly get averages that are more precise than the starting ratings so 4 should be average).