Finding two dimensions in MMPI-2 depression

This study examined the underlying structure of the Depression scale of the revised Minnesota Multiphasic Personality Inventory using dichotomous Rasch model and factor analysis. Rasch methodology was used to identify and restructure the Depression scale, and factor analysis was used to confirm the structure established by the Rasch model. The item calibration and factor analysis were carried out on the full sample of 2,600 normative subjects. The results revealed that the Depression scale did not consist of one homogeneous set of items, even though the scale was developed to measure one dimension of depression. Rasch analysis, as well as factor analysis, recognized two distinct content-homogeneous subscales, here labeled mental depression and physical depression. The Rasch methodology provided a basis for a better understanding of the underlying structure and furnished a useful solution to the scale refinement.