This study involved two phases: first when classification was based on the calibration sample, and second in a cross-validation setting. Computer-generated data were used. Results obtained from rules based on probabilities of group membership were compared for accuracy when classifying in the discriminant space and in the predictor variable spaces. In the first phase accuracy was greater in the predictor variable spaces, while the reverse was true in the second phase. In general, rules based on probabilities of group membership were approximately equally accurate, and more accurate than a rule related to a multiple regression analysis. Other findings are also discussed. (Author)