Fig. 4

Simulation 2: empirical relation of observed methylation entropy (OME) vs. mean methylation level (MML) in 500 simulated 4-CpG segments, under different sequencing depth m. Each dot/circle represents a CpG segment. Red color highlights the 50 CpG segments with no spatial correlation. Blue circles and black dots indicate the absence and presence of spatial correlation in the CpG segment by using the proposed chi-square test. For comparison, the analytical relation between methylation entropy and methylation probability is shown in solid lines, with blue curve standing for no spatial correlation (\(r=0\)) and 10 black curves from top to bottom corresponding to spatial correlations from weak to strong (\(r=0.1,\,0.2,\,\ldots ,\,1\)). A \(m=20\). B \(m=40\). C \(m=60\). D \(m=80\). E \(m=100\)