swh:1:snp:813359ba77493c9d5dd1abad9a1f53490a8abf57
Tip revision: 6bfd136e31efb7bca0e9c59e6d9b2b99e3f41f67 authored by Torsten Hothorn on 15 June 2005, 00:00:00 UTC
version 0.2-12
version 0.2-12
Tip revision: 6bfd136
rotarod.Rd
\name{rotarod}
\alias{rotarod}
\docType{data}
\title{ Rotating Rats Data}
\description{
The endurance time of 24 rats in two groups in a rotating cylinder.
}
\usage{data(rotarod)}
\format{
A data frame with 24 observations on the following 2 variables.
\describe{
\item{time}{the endurance time}
\item{group}{a factor with levels \code{control} and \code{treatment}.}}
}
\details{
The 24 rats received a fixed oral dose of a centrally acting muscle relaxant
(\code{treatment}) or a saline solvent (\code{control}). They were placed on a rotating
cylinder and the length of time each rat remains on the cylinder is
measured, up to a maximum of 300 seconds.
The rats were randomly assigned to the control and treatment group.
Note that the empirical variance in the control group is 0 and that the
group medians are identical.
This dataset serves as the basis of an comparision of the results of the
Wilcoxon-Mann-Whitney test computed by 11 statistical packages in Bergmann
et al. (2000). The exact conditional p-value is 0.0373 (two-sided) and
0.0186 (one-sided). The asymptotic two-sided
p-value (corrected for ties) is reported as 0.0147.
}
\source{
Reinhard Bergmann, John Ludbrook & Will P.J.M. Spooren (2000),
Different outcomes of the Wilcoxon-Mann-Whitney test from different
statistics packages. \emph{The American Statistician},
\bold{54}(1), 72--77.
}
\examples{
data(rotarod, package = "coin")
### Wilcoxon-Mann-Whitney Rank Sum Test
### one-sided exact (0.0186)
wilcox_test(time ~ group, data = rotarod,
alternative = "greater", distribution = "exact")
### two-sided exact (0.0373)
wilcox_test(time ~ group, data = rotarod, distribution = "exact")
### two-sided asymptotical (0.0147)
wilcox_test(time ~ group, data = rotarod)
}
\keyword{datasets}