A caution on the use of the MMPI K-correction in research on psychosomatic medicine

• Published in: Psychosomatic medicine 1989, Vol.51 (1), p.58-65
• Main Authors: MCCRAE, R. R, COSTA, P. T. JR, DAHLSTROM, W. G, BAREFOOT, J. C, SIEGLER, I. C, WILLIAMS, R. B. JR
• Format: Article
• Language: English
• Subjects: Adult; Aged; Aged, 80 and over; Biological and medical sciences; Defense Mechanisms; Female; Hostility; Humans; Longitudinal Studies; Male; Medical sciences; Middle Aged; MMPI; Neurotic Disorders - psychology; Nosology. Terminology. Diagnostic criteria; Psychology. Psychoanalysis. Psychiatry; Psychometrics; Psychopathology. Psychiatry; Psychophysiologic Disorders - psychology; Self Concept; Techniques and methods; Type A Personality
• ISSN: 0033-3174; 1534-7796
• DOI: 10.1097/00006842-198901000-00006

The MMPI K scale is widely used to screen for invalid responses and to adjust substantive scale scores for defensiveness. In a normal volunteer sample, correlations of MMPI clinical scales and the Cook-Medley Hostility (HO) scale with self-reports and peer ratings on the NEO Personality Inventory (NEO-PI) were decreased rather than increased by K-correction. Similarly, in a medical sample, structured interview-based ratings of Potential for Hostility were better predicted by uncorrected HO scores than by K-corrected HO scores. Finally, in a prospective study of mortality among lawyers, uncorrected HO scores were a significant predictor of all-cause mortality; K-corrected scores were not. The data suggest that, under some circumstances, the K scale may measure substantive traits rather than defensiveness, and should be used and interpreted with caution. Its use is probably contraindicated for most research on psychiatrically normal subjects.