Volcano plots of the distributions of the P-values resulting from the Wilcoxon signed-rank test versus the corresponding mean β-value difference for each CpG position. (a) Unadjusted data (72 CpG sites had a P-value <0.01 and mean β-value difference >0.05). (b) Data adjusted for buccal epithelium content using the PTPN7 CpG (131 CpG sites had a P-value <0.01 and mean β-value difference >0.05; pair 1 was excluded).
Souren et al. Genome Biology 2013 14:R44 doi:10.1186/gb-2013-14-5-r44