Figure 1. Bin size determination and distribution modeling.

a) Illumina reads from the Yoruban genome are not fit well by a Poisson model. b) Modeling the reads using a negative binomial distribution with a variance/mean ratio of 3 results in a much better fit, with a root mean square error three times smaller. c) The use of bin sizes that are too small results in an inability to cleanly separate peaks with copy number of one and two, resulting in a large number of false-positive calls in the overlapping region. d) Increasing the bin size allows us to trade resolution for better separation.