Noise is intensity dependent: Typical scatter plot for two experimental repeats. Each dot represents a gene, (a) repeat1 vs. repeat2, the black line is the diagonal (repeat1 = repeat2), (b) difference vs. mean intensity. The black lines are the running average of the standard deviation estimator (dataset used: GSE19921).
Zeisel et al. BMC Bioinformatics 2010 11:400 doi:10.1186/1471-2105-11-400