Distribution of differences of CLEVER results and those improved by ChopSticks. ChopSticks corrected some of breakpoints predicted by CLEVER so that the peak at zero became stronger. However, the distribution of differences of CLEVER results had long tail in 0–3000 bp and it was difficult for ChopSticks to correct such large differences. Here, k=2, f=0.5. Each frequency corresponds to the number of differences in bins of 20 bp.