Figure 4

The distribution of correlation coefficients values for a subset of genes/gene groups matched by two different probesets. Pearson's product-moment correlation coefficient r is on the x-axis and Spearman's rank correlation coefficient ρ is on the y-axis. Each dot represents correlation between expression values obtained with two different probesets corresponding to one gene on the Affymetrix U133A microarray in GSE1133 dataset. Black lines mark the quadrants that distinguish sets of genes behaving in one or another distinct way that sets them apart from each other. The quadrants were drawn according to correlation coefficient values. Values above 0.7 and below 0.3 were considered cut-offs. Number of genes that fell into each quadrant is shown in red color. Question marks represent the areas populated by genes with less deviant behavior that is evident from milder degree of decrepancy between correlation coefficients calculated using Pearson's coefficient r and Spearman's coefficient ρ. Dark red dashed line represents linear regression line and its equation is in the bottom right corner of the plot.