Personality Types and their Career Choices
The relevance of the MBTI for career planning has been questioned, with reservations about the relevance of type to job performance or satisfaction, and concerns about the potential misuse of the instrument in labeling individuals. In her original research, Isabel Myers found that the proportion of different personality types varied by choice of career or course of study.:40-51 However, some other researchers examining the proportions of each type within varying professions report that the proportion of MBTI types within each occupation is close to that within a random sample of the population.
Studies suggest that the MBTI is not a useful predictor of job performance. In 1991 three scholars at the University of Western Ontario analyzed the results of 97 independent studies that evaluated the effectiveness of personality tests in predicting job success and job satisfaction ("Personnel Psychology," winter 1991). The results of the nationwide study found that the MBTI was not an effective tool in predicting individual performance or satisfaction in a corporate setting: "The validity coefficient for personality tests in predicting job success was found to average 0.29 (on a scale of 0 to 1). The corresponding average validity for the MBTI, however, was a weak 0.12. In fact, each study that examined the MBTI found its validity to be below acceptable levels of statistical significance."  As noted above under Precepts and ethics, the MBTI measures preference, not ability. The use of the MBTI as a predictor of job success is expressly discouraged in the Manual.It is not designed for this purpose.