\title{Genomic Response to Brassinosteroid in Arabidopsis}
These data are from Affy ATH1 array experiments of genomic response to
brassinosteroid in Arabidopsis conducted by two laoratories.
The data set contains 500 random selected genes and 10 samples,
6 from lab 1 and 4 from lab 2. Data were pre-processed by RMA 


\item{arab}{matrix of gene expression levels of 500 genes 
from 10 samples, rows correspond to genes and 
columns to mRNA samples.}
\item{arab.cl}{numeric vector encoding the treatment classes, 
5 brassinosteroid-treated cases (code 1) 
and 5 control cases (code 0)}
\item{arab.gnames}{character vector containing the AffyID of 
the 500 genes for the expression matrix \code{arab}}
\item{arab.origin}{numeric vector encoding the origin of 
the samples, 6 samples from lab 1 (code 1) 
and 4 samples from lab 2 (code 2)} 
Nemhauser JL, Mockler TC, Chory J.  Interdependency of 
brassinosteroid and auxin signaling in Arabidopsis. 
\emph{PLoS Biol.} 2004 21460.
Microarray data from AtGenExpress