Violin plots of FAIRE and Pol II signals. (a-c) Violin plots (combining box plot and kernel density plot) show the uni-modal distribution of signals for probes entirely within introns and exons (spliced genes) or entirely within coding regions (unspliced genes) for FAIRE (a), Pol II occupancy (b), and H3K36me3 ChIP-chip signals (c). The median signal for probes in exons is shown by the dashed horizontal line. Signal differences (shown on the y-axis) between introns and exons (indicated by the bar and asterisk) are significantly different (P-value < 2.2 × 10-16; Welch two sample t-test).
Wilhelm et al. Genome Biology 2011 12:R82 doi:10.1186/gb-2011-12-8-r82