Validation of a brief form of the Competency Screening Test.

This study investigated the predictive validity of a brief, five item version of the Competency Screening Test (CST). Subjects were 140 defendants admitted to the forensic unit of a state hospital for evaluation of competency to stand trial. Scores on the brief version of the CST were used to predict competency decisions made by a multidisciplinary treatment team. In addition, the predictive validity of the brief version was compared with that of the standard CST. Both versions of the test exhibited significant relationships with staff decisions. However, the reliability of the brief version was lower than that of the standard CST because of the smaller number of items involved. Although the brief CST should not provide the sole basis for a decision about competency, it may be a useful component of a comprehensive program of competency evaluation, particularly when a rapid, preliminary screening instrument is needed.