Alternative scoring system of repeated items on the MMPI: caveat emptor

There are 16 items in the standard MMPI group forms which are included twice. It was found that a number of computerized scoring services use only the first occurrence of repeated items in scoring the MMPI scales, whereas the handscoring templates use an arbitrary combination of the first and second occurrence of these items. Comparison of these conventions suggested a potential for significant differences in score, particularly on the Sc scale. Scoring a set of 126 MMPIs of chronic pain patients by both of these scoring conventions revealed differences of up to 10 T points on the Sc scale. It is recommended that a single scoring convention for the MMPI be adopted by psychologists. For several reasons we suggest that only the first occurrence of repeated items should be used for scoring purposes. In the absence of a single convention, comparisons between Sc scores on different protocols should not be made without first insuring that the protocols were scored in the same manner.