Content and Comprehensiveness in the MMPI. An Item Factor Analysis in a Normal Adult Sample

The Minnesota Multiphasic Personality Inventory (MMPI) has become the most widely used instrument for personality measurement, although it was designed primarily to aid in the diagnosis of psychopathology. Several hundred research scales have been derived from the MMPI, despite the fact that until recently the size of the item pool precluded an adequate empirical analysis of its item content. To define its psychological content dimensions and evaluate the comprehensiveness of its items, we performed a principal components analysis of the 550 MMPI items on a sample of 1,576 male and female patients referred for coronary angiography. After an attempt to replicate Johnson, Butcher, Null, and Johnson's (1984)21-factor solution failed, nine orthogonally rotated components were interpreted. Agreement was found between a number of studies on several factors, including neuroticism, somatic complaints, cynicism, and religious orthodoxy. However, only one of the five personality dimensions identified by Norman (1963)was adequately represented. The nine factor scales identified in this analysis may be useful as an alternative way of scoring the test, especially for longitudinal studies with archival MMPI data sets. In the future, it would be advisable to supplement the MMPI with instruments that measure a broader range of normal personality characteristics.