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\name{contrMat}
\alias{contrMat}
\title{ Contrast Matrices }
\description{
Computes contrast matrices for several multiple comparison procedures.
}
\usage{
contrMat(n, type = c("Dunnett", "Tukey", "Sequen", "AVE",
"Changepoint", "Williams", "Marcus",
"McDermott", "UmbrellaWilliams", "GrandMean"),
base = 1)
}
\arguments{
\item{n}{ a (possibly named) vector of sample sizes for each group.}
\item{type}{ type of contrast. }
\item{base}{ an integer specifying which group is considered the baseline
group for Dunnett contrasts.}
}
\details{
Computes the requested matrix of contrasts for comparisons of mean levels.
}
\value{
The matrix of contrasts with appropriate row names is returned.
}
\references{
Frank Bretz, Torsten Hothorn and Peter Westfall (2010),
\emph{Multiple Comparisons Using R}, CRC Press, Boca Raton.
Frank Bretz, Alan Genz and Ludwig A. Hothorn (2001), On the numerical
availability of multiple comparison procedures. \emph{Biometrical Journal},
\bold{43}(5), 645--656.
}
\examples{
n <- c(10,20,30,40)
names(n) <- paste("group", 1:4, sep="")
contrMat(n) # Dunnett is default
contrMat(n, base = 2) # use second level as baseline
contrMat(n, type = "Tukey")
contrMat(n, type = "Sequen")
contrMat(n, type = "AVE")
contrMat(n, type = "Changepoint")
contrMat(n, type = "Williams")
contrMat(n, type = "Marcus")
contrMat(n, type = "McDermott")
### Umbrella-protected Williams contrasts, i.e. a sequence of
### Williams-type contrasts with groups of higher order
### stepwise omitted
contrMat(n, type = "UmbrellaWilliams")
### comparison of each group with grand mean of all groups
contrMat(n, type = "GrandMean")
}
\keyword{misc}
\keyword{Dunnett}
\keyword{Tukey}
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