Construct and incremental validity of the Rotter Incomplete Sentences Blank in adult psychiatric outpatients

The expression of positive vs negative attitudes in response to the 40 stems of the Rotter Incomplete Sentences Blank (RISB) can be scored and summed to an Overall Adjustment Score (OAS). By extending the validation of the OAS to adult psychiatric outpatients, this study demonstrates for the first time the incremental validity of a personality test over a simple self-rating. The RISB and six tests of adjustment were administered to 41 recent admissions to psychotherapy in two rural clinics. The tests of adjustment were selected to cover the two domains of symptoms vs function and the three methods of interview schedule vs objective inventory vs therapist ratings. Their scores were combined into an adjustment composite. The OAS related strongly to the composite in univariate regression, and moderately in hierarchical regression after covarying demographics, intelligence, social desirability, and self-ratings of adjustment. Construct validity was good, and incremental validity at least fair.