Performance of global models mapped to chemical space. Self-organizing map of Sets C, D, E, and F (from Figure 4) again colored by whether the molecule is in the Novartis set (Set C, orange) or is Ames+ (red) in the left box. In the right box, the SOM is colored by the mean absolute error of the predictions in the cell for the indicated model. Dark green indicates correct classification, yellow an equivocal prediction, and red an incorrect prediction. Cell mean absolute error is defined as the difference between the predicted probability of being mutagenic and the experimental class (0 or 1).