Figure 4.

Principal variance components analysis (PVCA) of the microarray data set (a) unnormalized, (b) quantile normalized, (c) ComBat-adjusted, and (d) DWD-adjusted. Contribution to variance was estimated for the following factors: run = experimental runs (run 1 to run 6), type = sample type (cancer or control), sex = female/male, age = age group (0–56, 56–64, 64–70, 70–100 years), smoking = smoking habit (current, never, former smoker), resid = residual weighted average proportion variance. Single factors were investigated as well as combinations of factors.