Comparing Three New MMPI-2 Randomness Indices in a Novel Procedure for Random Profile Derivation

This study compared three new validity indices; |F-Fb|, VRIN+|F-Fb|, and F+Fb+|F-Fb|; to the F, back-F, and VRIN according to their effectiveness in detecting degrees of profile randomness. Participants completed the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, and Kaemmer, 1989) according to standardized instructions. All profiles starting at Items 142, 284, or 426 were substituted with computer-generated random responses to produce 75%, 50%, and 25% random profiles, respectively. Twenty-five profiles were derived using 100% computer-generated items. Finally, one unaltered set of profiles was designated as 0% random. This generated five groups of MMPI-2 profiles, differing according to the degree of profile randomness (i.e., 0%, 25%, 50%, 75%, and 100%). Results showed that the F and |F-Fb| indices were unable to distinguish authentic from all degrees of randomness, whereas the F+Fb+F-Fb scale could reliably distinguish all levels of randomness. The actuarial analysis found back-F and F+Fb+|F-Fb| misclassified the least number of profiles, suggesting the latter index should be included in the evaluation of MMPI-2 profile randomness.