data transformation MA transformation An MA transformation is a data transformation which takes as input a collection of data points (g_1, r_1), (g_2, r_2), ..., (g_n, r_n) with the r_i and g_i positive real numbers, and whose output is the collection of data points (A_1, M_1), (A_2, M_2), ..., (A_n, M_n) where, for each i, A_i=(log(g_i)+log(r_i))/2 and M_i=log(r_i)-log(g_i). Here log denotes a logarithmic transformation. Elisabetta Manduchi PERSON: Elisabetta Manduchi MA transformation Philippe Rocca-Serra MA transformations are typically used in microarray data analyses. In this context, the g_i and r_i represent the reporter intensities in the two channels of a 2-channel assay or the reporter intensities in two related one-channel assays. Typically the base used for the logarithm is 2. pending final vetting