Figure 7
From: Functional normalization of 450k methylation array data improves replication in large cancer studies
Spatial location affects overall methylation. Quantiles of the beta distributions adjusted for a slide effect. The 12 vertical stripes are ordered as rows 1 to 6 in column 1 followed by rows 1 to 6 in column 2. (a) 10th percentile for type II probes for the unnormalized AML data set. (b) 15th percentile for type I probes for the unnormalized AML data set. (c) 85th percentile for type II probes for the unnormalized Ontario-EBV data set. (a–c) show that the top of the slide has a different beta distribution from the bottom. (d–f) Like (a–c) but after functional normalization, which corrects this spatial artifact. AML, acute myeloid leukemia.