Figure 4. ROC curve and variable importance for carcinogenicity prediction.

ROC curve of random forest classification in liver of: a) genotoxicity and b) carcinogenicity. For carcinogenicity, tissue specific class labels from the carcinogenicity potency data base (CPDB) were used. The red curves show the mean of the 200 reruns, whereas the dashed curves indicate the first and third quartile respectively. The teal dot indicates a classifier assigning equal costs to false positives (FP) and false negatives (FN) (zero-one loss), whereas the blue dot indicates a classifier assigning a cost of 5 for FN and 1 for FP. c) Variable Importance of the random forest model. Blue denotes genes that are down-regulated in the carcinogenic group, whereas red denotes up-regulation.