rma {affy}R Documentation

Robust Multi-Array Average expression measure


This function converts an AffyBatch into an exprSet using the robust multi-array average (RMA) expression measure.


rma(object,subset=NULL, verbose=TRUE, destructive = TRUE,normalize=TRUE,background=TRUE,bgversion=2,...)


object an AffyBatch
subset a character vector with the the names of the probesets to be used in expression calculation.
verbose logical value. If TRUE it writes out some messages. (Curently ignored)
destructive logical value. If TRUE works on the PM matrix in place as much as possible, good for large datasets.
normalize logical value. If TRUE normalize data using quantile normalization
background logical value. If TRUE background correct using RMA background correction
bgversion integer value indicating which RMA background to use 1: use background similar to pure R rma background given in affy version 1.0 - 1.0.2 2: use background similar to pure R rma background given in affy version 1.1 and above
... further arguments to be passed (not currently implemented - stub for future use)


This function computes the RMA (Robust Multichip Average) expression measure described in Irizarry et al Biostatistics (2003).

Note that this expression measure is given to you in log base 2 scale. This differs from most of the other expression measure methods.

Please note that the default background adjustment method was changed during the lead up to the bioconductor 1.2 release. This means that this function and expresso should give results that directly agree.


An exprSet


Ben Bolstad bolstad@stat.berkeley.edu


Rafael. A. Irizarry, Benjamin M. Bolstad, Francois Collin, Leslie M. Cope, Bridget Hobbs and Terence P. Speed (2003), Summaries of Affymetrix GeneChip probe level data Nucleic Acids Research 31(4):e15

Bolstad, B.M., Irizarry R. A., Astrand M., and Speed, T.P. (2003), A Comparison of Normalization Methods for High Density Oligonucleotide Array Data Based on Bias and Variance. Bioinformatics 19(2):185-193

Irizarry, RA, Hobbs, B, Collin, F, Beazer-Barclay, YD, Antonellis, KJ, Scherf, U, Speed, TP (2003) Exploration, Normalization, and Summaries of High Density Oligonucleotide Array Probe Level Data. Biostatistics .Vol. 4, Number 2: 249-264

See Also



eset <- rma(affybatch.example)

[Package affy version 1.8.1 Index]