FIGURE 2.

Effect of normalization on technical reproducibility. Data from brain and heart tissue samples were separated by quartile (Q1, Q2, Q3, Q4) based on the mean of unlogged unnormalized expression signal of the three technical replicates. Q1 corresponds to the bottom quartile and Q4 to the top quartile. Mean of log2 signal intensity (A) and standard deviation (B) of technical replicates were calculated for each normalization method, in each tissue and each quartile. VSN expression signals (in base e) were converted to base 2. (White) no normalization, (red) quantile, (blue) invariants, (cyan) scaling, (green) VSN.