Representative spatial heat maps and M-A plots of raw and normalized data. A, spatial heat map for a representative microarray slide before and after normalization. The footnote gives the range of M values for the slide (z-range) and the range excluding the extreme 5% tails of the distribution of M values (saturation) which are excluded from the plot. B, M-A plots for the same representative microarray slide before and after normalization. Green spots denote control genes and the coloured lines represent the curve for each print tip.