Prediction of Wiggins content scale scores from 168- and 399-item abbreviations of the MMPI.

Abstract

Multiple regression equations for estimating Wiggins content scores from 399- and 168-item abbreviations of Form R of the Minnesota Multiphasic Personality Inventory (MMPI) were derived for 100 patients and cross-validated in a separate sample of 50 patients. Across samples, Rs between 399-item short form scales and corresponding full scales were very high (median = .98 for the total sample), and the equations predicted accurately in cross-validation. Rs in estimating from 168 items were lower (median = .91 for the total sample), but the equations estimated mean content scores well in cross-validation. These results were viewed as indicating that there may be little loss in estimating from 399 items but that error in prediction may be unacceptably high for some of the 168-item short form scales. The correspondence of Wiggins scales and standard MMPI scales was also studied through regression analyses, and it was concluded that, although there is considerably overlap in the two sets of scales, inferences as to self-report content from the standard scales are not always simple or especially accurate.