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| + | ====== MA-plots ====== | ||
| + | **MA-plots** are used to study dependences between the //log ratio// of **two** variables and the //mean values// of the same two variables. The **log ratios** of the two measurements are called **M** values (from "minus" in the log scale) and are represented in the **vertical** axis. The **mean values** of the two measurements are called **A** values (from "average" in the log scale) and are represented in the **horizontal** axis. | ||
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| + | In microarray data contexts an MA-plot is used to compare //two channels of intensity measurements//. These two channels can be the **red** and **green** channels of one single chip of a two-color platform or the intensity measurements of two different arrays when using a single-channel platform. In a single-channel context at least two arrays are needed to draw a meaningful MA-plot. | ||
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| + | ====== References: ====== | ||
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| + | Yang,Y.H., Dudoit,S., Luu,P., Lin,D.M., Peng,V., Ngai,J. and Speed,T.P. (2002) Normalization for CDNA microarray data: a robust composite method addressing single and multiple slide systhematic variation. Nucleic Acids Res., Vol.30, No.4, e15. | ||
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| + | Bolstad, B. M., Irizarry, R. A., Astrand, M., Speed TP (2003). A comparison of normalization methods for high density oligonucleotide array data based on variance and bias. Bioinformatics 19, 185-193. | ||
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| + | ====== See also: ====== | ||
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| + | http://en.wikipedia.org/wiki/MA_plot | ||
