Irreproducible discovery rate between replicates. Left panel: number of significant peaks versus number of shared peaks called from both replicates. Right panel: number of significant peaks at different IDR cutoffs. 1: between biological replicates; 2: between pseudoreplicates from biological replicate 1, generated by randomly splitting the mapped reads into two equal-sized partitions; 3: between pseudoreplicates from biological replicate 2; 4: between pseudoreplicates from mapped reads merged from the two biological replicates. MACS called peaks at a p value cutoff of 1e-3, instead of the default 1e-5.