The JVR research department has recently finished a study aimed at investigating the psychometric functioning of the MBTI Form M in South Africa. Both Classical Test Theory (CTT) and Item Response Theory (IRT) techniques were employed for this purpose. A brief summary of the results are described below, however the technical report can be requested from JVR’s research department. A full academic article on this research has been submitted for review to the SA Journal of Industrial Psychology. Starting with reliability, Cronbach alpha coefficients were calculated for each of the scales on the MBTI instrument. Reliability estimates were also calculated for each of the scales across different ethnic, age and gender groups. In all cases, each of the type preferences demonstrated reliability estimates above .80. With regards to construct validity, exploratory factor analysis revealed that all the items on the MBTI instrument had primary loadings on their posited factors, apart from two S-N items. No items had salient secondary loadings on another factor. The pattern of loadings closely resembles the theoretical structure of the MBTI instrument and represents good evidence for construct validity from a CTT perspective. Further support for the construct validity was demonstrated with IRT techniques. In particular, Rasch analysis found no evidence of misfit for any of the items on the four scales. This shows that a single line of enquiry runs through each of the MBTI scales. Differential item functioning was investigated across gender and ethnic groups. Some evidence of DIF was found between gender and ethnic groups however there was no consistent direction to the DIF items since they were divided almost equally between the groups. This pattern indicates that the DIF does not translate to bias at the scale or test level. Type distribution was also investigated and it was found that the most frequently occurring type preference for White and Black respondents, as well as the overall group, was ESTJ followed by ISTJ. With regard to group differences in type, both Black and White respondents tended to report preferences for Sensing, Thinking, and Judging over Intuition, Feeling, and Perceiving, although these differences in reported type were more pronounced for the Black South African group. Overall, this study found good evidence for the psychometric functioning of the MBTI Form M, which supports the conclusion that the MBTI instrument is indeed appropriate for use in the South African context. For more information you can leave a comment or contact: Casper van Zyl -