Prediction scores. (A) Data from all bortezomib-treated patients analyzed in bootstrap; the empirical distributions of prediction accuracies for all test sets are shown. Note that the median value of the accuracies for the correctly labeled samples (70.2%) is higher than 95% of the accuracies for the permuted sample labels (95th percentile = 69.4%). Thus, the 2 distributions are significantly different. (B) A classifier for trials 025 and 040 was used to predict the response of patients receiving bortezomib and patients receiving Dex in trial 039. Accuracy of response prediction for bortezomib-treated patients is significant (P < .033; 75% overall accuracy) but not significant (P = .53; 57% overall accuracy) for patients treated with Dex. No significant accuracy is observed when all test samples are simply predicted as the most popular response category (P > .999).