Partitioning of variation in hybridization ratio. Two sources of variation affect the quantitative prediction of sequence divergence from hybridization ratios. A) Schematic representation of the "technical error" (the standard error of the fit of the hybridization ratios for that feature among technical replicates) and the variation due to physical characteristics of each probe and sample DNA (DNA hybridization kinetics: the deviation from the regression line of hybridization ratio vs. %ID). B) The calculated relative contributions of technical error (grey line) and variation due to DNA hybridization kinetics (black line) as a function of %ID of D. yakuba to D. melanogaster (SD: standard deviation). At low %ID, DNA kinetics predominates.