A cross-validation of the keane and penk MMPI scales as measures of post-traumatic stress disorder

The scores of DSM‐III‐diagnosed post‐traumatic stress disorder (PTSD) patients (N = 116), psychiatric patients who did not meet the criteria, and normals (N = 19) on the Keane, Malloy, and Fairbank (1984) PTSD and Penk Combat scales for the MMPI were compared. The Keane scale discriminated PTSD‐positive patients from normals at a substantial level of accuracy (ω2 = .23; mean hit rate = 80.50%) and PTSD‐positive from PTSD‐negative patients at a more modest level (ω2 = .09; mean hit rate = 64%). The scores of the PTSD‐positive and PTSD‐negative patients were considerably lower than those of Keane et al.'s (1984) samples, which sugggests that local norms may be needed to facilitate their interpretation. The Penk Combat Intensity scale, which was correlated highly with the Keane scale, differentiated the PTSD‐positive patients from both the normals and the PTSD‐negative patients, but with less differentiating power (ω2's = .07 and .08). The Penk Combat Exposure scale did not separate the groups.