MA-plot followed by linear regression. (a) The MA plot of all the bin count data before normalization. (b) The MA plot of all the bin count data after normalization. The adjusted M value is the raw M value at each data point minus the fitted value from the regression line. (c) The three-component normal mixture model fitted to the adjusted M values after normalization. The blue line shows the real density. The green line shows the fitted density, which is the sum of the three individual components shown as red lines.