Fold change analysis of microarray data. Clustered image maps derived from gene array analysis of 15 canine osteosarcomas. Data was preprocessed with PLIER (A) and RMA (B) algorithms. Probesets were selected based upon fold change > 3 (PLIER) or > 2 (RMA) and an uncorrected p-value < 0.05. (C) Number of probesets meeting selection criteria from each algorithm that were shared and unshared between the two.