Construct validity of the MMPI-168(L) with mentally retarded adults and adolescents

Fifty-three persons residing in an institution and diagnosed with mild or moderate mental retardation were assessed with a modification of the MMPI-168. Forty-one of the residents also had psychiatric diagnoses. Construct validity of the MMPI-168(L) was examined by correlating T scores obtained on the scales of this instrument with the results of an 8-item "Behavioral Survey." The survey required unit clinicians to rate the severity of behavioral disturbance in eight categories. Six of the items on the "Behavioral Survey" were found to correlate with one or more MMPI scales. Stepwise multiple regression procedures revealed additional collective relations between elevations on the MMPI and ratings of behavioral disturbance.