\name{maNormMed}
\alias{maNormMed}
\title{Median location normalization function}

\description{
This function is used for location normalization using the median of 
intensity log-ratios for a group of spots. The function should be used 
as an argument to the main normalization function \code{\link{maNormMain}}.
}

\usage{
maNormMed(x=NULL, y="maM", subset=TRUE)
}

\arguments{
  \item{x}{Name of accessor method for spot statistic used to stratify the 
data, usually a layout parameter, e.g. \code{maPrintTip} or \code{maPlate}. 
If \code{x} is not a character, e.g. NULL, the data are not stratified.}
  \item{y}{Name of accessor method for spot statistics, usually \code{maM}.}
  \item{subset}{A "logical" or "numeric" vector indicating the subset of points   used to compute the location normalization values. }
}


\value{
A function with bindings for the above arguments. This latter function takes as 
argument an object of class \code{"\link{marrayRaw}"} (or possibly 
\code{"\link{marrayNorm}"}), and returns a vector of fitted values to be 
subtracted from the raw log-ratios. It calls the function \code{\link{maMed}}, 
which is not specific to microarray objects.
}

\references{S. Dudoit and Y. H. Yang. (2002). Bioconductor R packages for 
exploratory analysis and normalization of cDNA microarray data. 
In G. Parmigiani, E. S. Garrett, R. A. Irizarry and S. L. Zeger, editors, 
\emph{The Analysis of Gene Expression Data: Methods and Software}, Springer, 
New York.\cr \cr

Y. H. Yang, S. Dudoit, P. Luu, and T. P. Speed (2001). Normalization for cDNA 
microarray data. In M. L. Bittner, Y. Chen, A. N. Dorsel, and E. R. Dougherty 
(eds), \emph{Microarrays: Optical Technologies and Informatics}, 
Vol. 4266 of \emph{Proceedings of SPIE}.\cr \cr

Y. H. Yang, S. Dudoit, P. Luu, D. M. Lin, V. Peng, J. Ngai, and T. P. Speed 
(2002). Normalization for cDNA microarray data: a robust composite method 
addressing single and multiple slide systematic variation. 
\emph{Nucleic Acids Research}, Vol. 30, No. 4.
}

\author{Sandrine Dudoit, \url{http://www.stat.berkeley.edu/~sandrine}.}


\seealso{\code{\link{maNormMain}}, \code{\link{maMed}}, \code{\link{median}}.}

\examples{
# See examples for maNormMain.

}
\keyword{univar}
\keyword{robust}