miRNA 5'-end cutting accuracy comparison between Drosha and Dicer in humans and flies. The bars show the mean value of 5'-end heterogeneity mature miRNAs defined by Dicer (left bar) or Drosha (right bar) in humans (Figure 4A) and flies (Figure 4B). For each miRNA, the heterogeneity was calculated as described in Methods. In the Figure 4A and Figure 4B, the Y-axis is the heterogeneity value, the top, middle and bottom lines of each box correspond to the first quartile, median, and the third quartile of observations, respectively. The vertical lines extend to the most extreme data points within 1.5 times the range between the first and the third quartiles. Data points outside this range are not shown.