MA plot

MA plots are used to visualize intensity-dependent ratio of raw microarray data. The MA plot uses M as the y-axis and A as the x-axis where M and A are usually defined as: $$\textstyle{M=log_2 R - log_2 G}$$ $$\textstyle{A=\frac12 \times (log_2 R + log_2 G)}$$