Effect of negative variation normalization. A – Decreasing rank differences in the comparison Wt-t0b vs Wt-t0a are plotted (in blue) against the rank of Wt-t0a and decreasing rank differences in the comparison Wt-t0a vs Wt-t0b are plotted (in red) against the rank of Wt-t0b. A sliding window of 100 points was moved by steps of 30 points. At each position, the mean (lower magenta curve) and std (upper green curve) were plotted and the resulting jagged lines were smoothed by a fitting procedure . The vertical arrows indicate the position of 10, 100 and 1000 signal on the 0–100 rank scale. B – Distribution of zRD (mean (magenta curve) and std (green curve) are not smoothed).