Assessing the person reliability of an individual MMPI protocol

This study investigated various measures commonly employed to assess the person reliability of an individual Minnesota Multiphasic Personality Inventory (MMPB protocol. Specifically, relationships among indices of person reliability and the standard MMPI validity scales were examined using the responses of 82 subjects who completed the MMPI on two occasions separated by 1 week. Person reliability indices were based on within-occasion responses to identical and to psychologically similar items, and on three across-occasion response consistency measures. The validity scales, namely, the L, F, K, and Cannot Say scales, showed higher test-retest stability than the within-occasion person reliability indices. Further, the validity scales and person reliability indices appeared to reflect multiple facets of dependable responding. Interestingly, an individual's tendency to change responses to MMPI items from the test to the retest was significantly predictable. Clinical implications of these findings were derived.