Incremental validity of the new MCAT.

The authors investigated the power of the New Medical College Admission Test (MCAT) to predict performance of first-year medical students at the University of North Carolina. The approach was to compute the additional variance in performance explainable by the New MCAT after the effects of other routinely available admissions variables were taken into account. This incremental validity of the New MCAT was found to be substantial, with performance prediction improved by 23 to 38 percent, and was higher in this range when nationally standardized performance measures were employed as the outcome variable. Also several predictor variables--including two New MCAT subtests--were found to have significant polynomial relationships to the outcome measures; Use of polynomials in the regression procedure increased the overall accuracy of the prediction but did not affect the incremental validity of the New MCAT.