An evaluation of the usefulness of the MMPI-2 F(p) scale

The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) F(p) scale was developed by Arbisi and Ben-Porath (1995) by identification of 27 items endorsed by fewer than 20% of individuals in both normal and psychiatric samples. The F(p) scale was designed for applications in settings characterized by high base rates of serious psychopathology, such as psychiatric inpatient units, and is proposed as a useful scale in discriminating overreported protocols from those produced by patients with serious psychopathology. In this study we investigated the characteristics of this scale in a sample of 617 psychiatric inpatients who responded to the MMPI-2 under standard conditions, and 203 overreported protocols derived in research studies conducted with normal adult participants instructed to simulate various forms of serious psychopathology. Results of this study are consistent with prior reports of a relatively low frequency of item endorsement for F(p) scale items in psychiatric samples, and intercorrelations between the F(p) scale and the MMPI-2 basic clinical scales in clinical samples that are generally lower than those produced between either F or Fb and the basic clinical scales. However, this intercorrelational pattern between F(p) and the MMPI-2 basic scales was not as consistent for the overreported sample. Additionally, the F(p) scale appears to be effective in discriminating overreported from accurate MMPI-2 protocols, with some evidence that the optimal cutting scores for this and other MMPI-2 infrequency scales may differ as a function of gender. Finally, these findings do not show clear evidence of improved group prediction derived from the use of the F(p) scale in contrast to results obtainable through the use of the MMPI-2 F scale.