Average Spearman's correlations between MA and qRT-PCR detection of differentially expressed genes. Plots present average correlations between values of Welch's t-statistic calculated from MA and qRT-PCR measurements. Average values were calculated for each of the 6 preprocessing algorithms over the 6 data sets in each of the 6 filtering/mapping methods. Panel A shows results for the old annotation while panel B presents results for the new annotation. Curves are coloured and numbered to indicate the preprocessing algorithms.