Processing screen data to remove biases associated with differential hairpin abundance. Plotting of the log ratio of paired samples (for example, reference-depletion) frequently revealed biases with respect to average hairpin abundance. Consequently, the data were normalized using loess regression to remove this bias. (a) The loess fit lines from four biological replicates of a 10k pool viability screen in MCF7 cells when the log ratio is plotted against log mean hairpin abundance. (b) The same plot post-loess normalization showing the standardization of the curves.