ROC curves constructed by thresholding BioNJ bootstrap-based confidence values. Best tree branch classifiers (i.e., that are able to associate higher confidence values to true branches than to false branches) are those that maximize the area under the ROC curve (AUC). For each simulation case, the AUC is given under the corresponding ROC space representation. For each column, the best (i.e. higher) AUC is written in boldface characters. AUCs that are not significantly different to this best value (as assessed by a Z test) are underscored.