Does the MMPI PTSD-PK scale measure robustness?

Research evaluating the diagnostic value of the MMPI PK scale for determining Posttraumatic Stress Disorder has been consistently positive. Various cutoff points have been suggested, depending on the population studied. The current study, involving a select group of police candidates from middle-sized midwestern towns, suggests that low PK scores may represent robustness. These subjects as a group made low use of health and mental health services and obtained very low PK scores (T = 41), although they made average scores on the clinical scales.