COMPARABILITY OF MMPI AND MMPI-2 PROFILE PATTERNS - BEN-PORATH AND TELLEGENS INAPPROPRIATE INVOCATION OF MAHALANOBISS D-2 FUNCTION

Ben-Porath and Tellegen (1995) claimed that the data in the article by Humphrey and Dahlstrom (1995) were improperly analyzed by means of Q correlations between raw scores earned by the individuals in the foren sic sample to establish pattern comparability between the original Min nesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1 943) and the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Bu tcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989), which were then contrasted with Q correlations between the corresponding T-score patte rns. Ben-Porath and Tellegen (1995) contended that the Q correlation i s affected by random factors and that a generalized distance function, D-2, is the only legitimate index of profile comparability. Data are presented here to show that the Q correlation serves as a reliable ind ex of pattern comparability, relatively unaffected by differences in p rofile elevation. The Mahalanobis (1936) D-2 index is too heavily weig hted with differences in profile elevation to serve as the proper inde x of equivalence in profile patterning. The findings in the Humphrey a nd Dahlstrom (1995) article were based on appropriate data-analytic pr ocedures because the primary concern in their investigation was the ex tent to which the patterns of T-score profiles from the original MMPI and the MMPI-2 are comparable when the raw-score patterns are virtuall y identical.