Measurement of personal competence of mentally retarded individuals.

The development and validation of the Personal Competency Scale, a 20-item rating instrument designed to assess competence of mentally retarded adults, was described. This broad bandwidth measure provides scores on three factorially derived domain scales, which are consistent with the rationale underlying the instrument's development, and a total score. The three major dimensions of personal competence delineated were adaptive, cognitive, and affective competence. Reliability estimates in the form of interrater, test-retest, and internal consistency were high, ranging from .80 to .94 for the subscales and .90 to .97 for the total scale. Correlations between the Personal Competency Scale and criterion variables, including IQ and Adaptive Behavior Scale scores, ranged from .61 to .75. Multiple regression and canonical correlations of .85 and .87, respectively, also strongly support the validity of this new measure.