ROC curve for prostate cancer classification (Gleason 5 vs. Gleason 7). ROC curves for prostate cancer classifcations (Gleason 5 vs. Gleason 7 cases) were constructed for the proposed GDFS method (blue), CFS (green), and rpart (orange). In each case, the posterior probability of belonging to the Gleason 7 group was calculated for each observation j using features selected, and model parameters estimated, with observation j omitted (leave-one-out cross-validation). ROC curves were constructed from these posterior probabilities using the ROCR package in R . ‘X’ marks the 0.5 classification threshold on each ROC curve.