Figure 4

Data distribution before and after quantile normalization. Example of expression changes in a dataset before and after quantile normalization, and a frequency histogram of an average distribution fit to all datasets. A) Data from a sample dataset plotted before (X-axis) vs. after (Y-axis) quantile normalization. No major distortions were observed, quantile normalization introduced only transitional rescaling to the data; B) An average distribution fitted to all datasets. This distribution allows setting global noise threshold and directly comparing expression levels across the datasets.