Application of decision theory to DUI assessment

The application of decision theory to screening of driving under the influence (DUI) offenders is illustrated in an evaluation study that investigated the validity of a structured interview and a survey instrument. These findings are examined graphically using the relative operating characteristic (ROC). This graph relates the proportion of true-positive cases to the proportion of false-positive cases for various placements of the decision cut-off score. The ROC's two principal parameters, test sensitivity and examiner bias, are used to provide a complete quantitative description of the performance of two screening instruments. A major goal of this study is to show how a new measure of examiner bias, the "cost ratio," improves the evaluation of DUI screening programs.