Sept. 24, 2021 – This all sounds good. A simple classification system for understanding people’s personality ought to be a great tool for people to understand themselves and for managers to get to know their reports. Anything that helps people recognize the ways in which their motivations differ from those of the people around them should be useful in resolving conflicts and influencing behavior.

Unfortunately, the MBTI is a bad tool in ways that are likely to be misleading.

The discipline of personality psychology is a real success story in the field of psychology. Constructs like the Big Five personality characteristics (Openness to experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism) have been measured, replicated, and studied extensively for decades. Starting with observations about individual differences, the field has also made strides toward understanding the motivational basis of these constructs.

There are a few key lessons from personality psychology that undermine the MBTI. First, a good personality inventory needs to have test-retest reliability. That is, when you give an inventory to the same person over time, you’d like to get similar results. The Big Five (for example) is very stable across the lifespan, even though it drifts a bit over time. In contrast, the various forms used to measure the MBTI vary in their reliability, but for many of them, the reliability is quite low.


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