Smooth scatterplots for estimated standard deviation vs. actual distance to nearest motif site. (a) STAT1. (b) NRSF. (c) ZNF143. Both axes truncated values at 250 bp. For all datasets, the estimated standard deviation and the actual distance to the nearest motif site had a positive Pearson correlation coefficient. Dark regions represent high densities of data points and small dots represent isolated points. The majority of data points are located at the bottom-left corner for all three panels, hence most standard deviation estimates are small and actual distances to the motif site are also small in general.