Invalid elevations of the F scale on an MMPI profile of a psychiatric inpatient. Are they always "invalid"?
SIOUSIOURA D., TASOULAS ST., VALLIANOU D., PAPAGEORGIOU G.

Psychometric evaluation in clinical settings such as a Psychiatric Department of a General Hospital has become widespread. There are substantial reasons for that: the established great reliability and validity of the commonly used psychometric tests; the significant contribution of personality disorders in the clinical population; the interdisciplinary approach in diagnosis management and even the noteworthy interest of clinical psychologists in the evidence-based use of clinical instruments.

The Minnesota Multiphasic Personality Inventory (M.M.P.I.) is probably the most widely used psychometric instrument in clinical settings. A relative benefit is the consideration of the reliability and validity indices (L, F, K). When taken into account, those valuable tools can convey not only critical information about the reliability of the psychometric procedure, but also clinical matters of great importance. This is extremely weighty, in cases of coadministration of the M.M.P.I. with another psychopathological instrument, such as the Personality Diagnostic Questionnaire (P.D.Q.).

The validity F (Infrequency Scale) index on the M.M.P.I. encompasses items which describe thoughts, behaviors, ideas, reflections and emotions whose endorsement substantially differs from the social norm. The statistical degree of difference can be translated into significant clinical information about the reliability of test results. It is also linked to the current psychopathological state of the test taker.

The quick dismissal of an M.M.P.I. profile when one of the validity indices (such as F) is extremely deviant is not rare, especially among less experienced mental health professionals-users of the instrument. With this case study, a special psychopathological M.M.P.I. profile is presented; the extreme elevation of the F index, instead of cancelling the profile, contributes to a more valid psychological assessment.

The M.M.P.I. valid profile interpretation has been enhanced by the co-administration of the Personality Diagnostic Questionnaire, an international psychometric instrument which serves for the diagnosis of Axis II psychiatric disturbances. The psychopathological personality traits which are captured by the PDQ assessment are then taken into consideration with the M.M.P.I. profile (codetype).

The PDQ-4 is a DSM-based psychopathology instrument of personality disorders or traits. Its relative easiness of use, its time effectiveness and the interpretation according to very objective measures prove very useful in clinical settings. PDQ has been recently translated into the Greek language.

In the case we present in this paper, the Infrequency Scale of the M.M.P.I. deviates enormously from the statistical (and clinical) norm. Such a divergence can be explained, though, by the great range of the patients' psychopathological personality traits. The very wide (and unusual) distribution of the patient's problematic thoughts and behaviors across the clinical spectrum produced such an F index.

The evidence from the clinical interview and the PDQ analysis came to substantiate the patient profile. Without the administration of the PDQ instrument, the profile could have been easily (and of course "legitimately") discarded as "invalid".

The extreme deviation of F (>100) does not automatically discard an M.M.P.I. profile. On the contrary, it can suggest fictitious disorder, malingering, "fake bad behaviors", psychosis with extremely productive symptomatology and principally, a heavy personality disorder. Great caution is required in the interpretation or dismissal of such profiles, especially in psychiatric care units. Encephalos 2008, 45(4):241-245.

Key words: M.M.P.I., PDQ, case study, reliability F index.