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. Author manuscript; available in PMC: 2015 Dec 1.
Published in final edited form as: Cancer Epidemiol Biomarkers Prev. 2014 Dec;23(12):2622–2631. doi: 10.1158/1055-9965.EPI-14-0464

Figure 2. Principal component analysis (PCA) to identify the sources of variation in methylation β-values across the three patient samples and all conditions.

Figure 2

Patient samples are denoted by shape (A – circle, B – triangle and C – diamond). (a) Scatter plot of samples in the first and second principal components (PC1 and PC2), which account for 36.6% and 27.8% of the variation. (b) Scatter plot of PC3 and PC4, which explained 5.9% and 3.9% of the variation with separation by tissue storage type (FF vs. FFPE) as well as the ligation method (LIG vs. RES).