\HeaderA{labelParams}{Remove labelling variables}{labelParams}
\keyword{models}{labelParams}
\begin{Description}\relax
This function removes any categorical variables which have
the same number of levels as there are samples (labelling variables).
\end{Description}
\begin{Usage}
\begin{verbatim}
  labelParams(pData) 
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{pData}] An object of class
\code{\LinkA{phenoData}{phenoData}} containing the
phenotypic information for the experiment.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The \pkg{Envisage} package contains methods allowing the use of linear
models (LMs) for analysing significantly changing genes in experiments
with a variety of sources of variation, be they experimentally
controlled variables such as drug treatment or time, or non-controlled  
sources of confounding variation such as phenotypic or environmental 
differences. This allows all sources of variation to be considered when 
analysing for significant differential expression, ensuring resulting
genes are biologically relevent to the experimental question.

The function \code{\LinkA{labelParams}{labelParams}} ensures that any
categorical variables included by the user for model fitting that have
the same number of factor levels as there are samples are removed
prior to fitting the model. Such labelling variables contain a unique
value for each sample, and will this result in a perfect fit for the
data. 

\code{\LinkA{labelParams}{labelParams}} is an internal function and is not
designed to be accessed by users.
\end{Details}
\begin{Value}
A vector is returned containing the indices of the labelling
parameters for the \code{\LinkA{phenoData}{phenoData}}
object \code{pData}.
\end{Value}
\begin{Author}\relax
Sam Robson \email{S.C.Robson@warwick.ac.uk}
\end{Author}
\begin{References}\relax
Robson, S. C., Hunter, E., Bird, H., Turner, H. (2008) 
\emph{Envisage: model-based significance analysis of microarray gene
expression data}, manuscript in preparation
\end{References}
\begin{SeeAlso}\relax
For the main \pkg{Envisage} method, see \code{\LinkA{envisage}{envisage}}.
\end{SeeAlso}

