Figure 4From: Accuracy of cDNA microarray methods to detect small gene expression changes induced by neuregulin on breast epithelial cellsControl correction of each spot markedly improves the distribution of log ratios. (A) Histograms show that T/C and C/C log ratio distributions after lowess normalization still have a marked asymmetry with a larger tail towards the left (increased down-regulated genes). The distribution becomes symmetric after subtracting the log (C/C) from the log (T/C). (B) Quantile-quantile plots similarly show that the log ratio distribution becomes more normal after correction of each spot with the control ratio.Back to article page