Factoid: The Myers-Briggs test fails the most basic criteria for
validity. A person who pays attention in just one undergraduate-level class on test design will be able to point out a number of fatal flaws (trust me,
I should know!) Despite that, a lot of
people seem to find it useful. Go figure.
Since people were curious, I've explained a small bit about how to design a psychological test. If you read this, the failures of the Myers-Briggs will be obvious.