How was MBTI determined to have 16 personalities?

This is a type of test that will provide you with questions that you can only answer two ways. This means that you have to choose between the two whether or not the answer is accurate to what you would actually do or what you actually are like.

There are four dimensions that are available and the personality type will be determined based on your results on the various dimensions that will appear to you. You can get to know the different personality types that are available. You can also take the test in order to know what your personality type is going to be. Just remember that things will not always be accurate.

Basically 4 x 4. The test presents you with questions that have forced choice answers, that is you can only answer in two different ways. Your choices (preference or tendency for one way or another) on each question places you in one of four bi-polar dimensions: Extraversion/Introversion E-I; Sensing/Intuition SN; Thinking/Feeling T-F; Judging/Perceiving J-P. Your personality type results from the cross-products of these four dimensions.

For instance, if your answers favour Extraversion, Intuition, Feeling and Judging responses, your personality type would be ENFJ: an easy communicator, possibly overly idealistic, focused on ideas and concepts rather than facts and details; decisions based on feelings and values (Feeling) and organized rather than spontaneous. ENFJs are sometimes referred to as Teacher personalities because of their interest in helping others develop and grow.