Psychometric adequacy and comparability of the short and full forms of the Personality Assessment Inventory.

The 160-item short form of the Personality Assessment Inventory (PAI) was developed for situations in which respondents complete only the 1st half of the test. The present study evaluates the adequacy and comparability of the full and short forms of the PAI in terms of a wide range of psychometric characteristics. In all, 421 participants completed the full form as part of a neuropsychological evaluation. Results indicated slightly lower internal consistency reliability of the short compared with the full form. Group-level agreement of short and full form scales ranged from adequate to excellent. However, within-subject agreement was somewhat more variable. Low levels of within-subject agreement were strongly associated with elevated validity scale scores. The factor structures of the full and short forms showed high congruence for a 3-factor solution. These findings suggest that many scales of the short form have adequate comparability with their respective full form scales. However, low levels of reliability across less impaired ranges of the latent trait, diminished content coverage, and altered validity detection may limit the utility of some of the short form scales.