A 25-Year Review and Psychometric Synthesis of the Myers–Briggs Type Indicator (MBTI) – Form M

Abstract

The Myers–Briggs Type Indicator – Form M (MBTI-M) is the most popular personality assessment used by professional counselors and taught in counselor education programs. Still, little is known about MBTI-M score reliability and validity beyond what is published in the test manual. This psychometric synthesis aggregated the results across 193 studies from 1999 to 2024 using the Myers–Briggs Type Indicator (MBTI) Form M. Internal consistency was 0.845–0.921 across subscales and total scores. Convergent evidence with similar constructs were robust across six personality instruments. Proportions of types and subtypes were aggregated from 178 articles with an aggregated n of 57,170 participants and compared to the normative proportions (n = 3009) published in the manual. Structural validity and test-retest studies were absent from the 25-year literature sampling.