Fraction of variation associated with principal components. Fraction of variation associated with principal components after adjustment for the top component which captures the inherent bi-modality of the methylation distribution. Red denotes the observed values, black denotes those obtained by randomly scrambling up the data matrix. Each black dot represents the value of 10 distinct randomisations, which all yield the same value as singular values represent measures of global variation which themselves are invariant under a global randomisation of the data.
Bell et al. BMC Medical Genomics 2010 3:33 doi:10.1186/1755-8794-3-33