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 cut-off 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.