ROC curves for aberration calling. ROC curves for the classification of 2936 uniformly spaced genomic loci into three categories (a) deletion, (b) normal and (c) amplified. Using a fixed threshold T across the genome, every locus was called as a deletion if the PCF value was less than -T and as an amplification if the PCF value was larger than T. For every panel in the figure, one of the platforms is chosen as the correct classification (Agilent in row 1, ROMA/NimbleGen in row 2, and Illumina in row 3). The ROC curves show the ability of each of the remaining two platforms to mimic this correct classification. There are four curves in each panel, corresponding to the thresholds T = 0.25, 0.50, 0.75, 1.00 (shown in blue, green, red and cyan, respectively) used to define the correct classification. The points on a ROC curve correspond to different choices of T for the other platform under consideration.