Effect of data transformation on biological heteroscedasticity. A: power transformed data. B: log transformed data. The standard deviations over all glucose experiments were ordered by the mean value of the peak areas and binned per 10 metabolites. The first bin contained the metabolites whose peak area was below the detection limit.
van den Berg et al. BMC Genomics 2006 7:142 doi:10.1186/1471-2164-7-142