Why we will not run MBTI for you
It is asked for by name more than any other instrument. Its test–retest reliability is the reason we say no, and what we offer instead.
by Dr Aileen Struthers
Why we will not run MBTI for you
The Myers-Briggs Type Indicator is the most requested instrument in our enquiries and the only one we decline outright. That deserves an explanation rather than a policy line.
The problem is not that personality instruments are useless. It is that MBTI sorts people into binary types on four dichotomies where the underlying traits are continuous and most people sit near the middle. When you cut a normal distribution at its mean, small measurement error flips the category. Published test–retest studies have found a substantial minority of people receiving a different four-letter type when retested weeks later.
A development conversation built on a category that unstable is a conversation built on noise. Worse, the four letters are sticky: people remember and repeat their type for years, and it becomes a reason not to change. "I am an introvert" is a sentence we hear used to decline the exact practice that would help.
What we use instead, when a trait instrument genuinely adds something: a five-factor measure reported as percentiles with confidence bands rather than as types. It is less satisfying, harder to put on a mug, and it does not tell anyone who they are. It tells them where they currently sit relative to a comparison group, which is a usable thing.
And often the honest answer is that no instrument is needed. Most of what a leader needs to hear is available from four well-run conversations with the people they work with, and it is specific in a way a questionnaire cannot be.
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