Profile of the normal-exponential two-peak (NEXT-peak) density. (a) An example of NEXT-peak density profile without fitting to a particular dataset. The blue curve is for a tag profile on the left (positive) strand, the red curve is for the right (negative) strand. Parameter values are β = 60, and σ = 40 (see Methods). The two density curves mirror each other around the center location. (b) Tag profile of STAT1 ChIP-seq data. From the motif search, thousands of motif sites were found. The cumulative tag counts were rescaled and displayed as densities. (c) NRSF. (d) ZNF143. Table 2 reports estimated values and for each dataset.