- The MMPI-2 post-traumatic stress disorder scales (PK and PS) were examined with a sample of 96 outpatient anxiety disorder and 97 outpatient traffic accident subjects. PK and PS correlated .96 and showed highly similar correlations with MMPI-2 validity, clinical, content and supplementary scales for both groups, which indicated that these scales are indices of MMPI first-factor variance. This was supported by separate principal components analyses for each group, in which PK and PS contributed the most variance to the first component. Although the groups showed different MMPI-2 mean profiles, neither PK nor PS contributed to discriminant function classification of group members. It is suggested that PK and PS are indices of general emotional distress and maladjustment; implications for their use in diagnosing post-traumatic stress disorder were discussed.