Impact of perturbation variability on discriminant score. Distributions are shown of the discriminant score xTw for each of the 106 validation samples of the Rosetta dataset, when using a nearest centroid classifier built on the 70-gene profile of , over 1000 perturbations. Perturbed expression data is based on the Rosetta error model. Red dots indicate the discriminant scores corresponding to the unperturbed expression data. The blue boxes indicate samples with a map-score of at least 25%.