\name{trees}
\title{Girth, Height and Volume for Black Cherry Trees}
\usage{data(trees)}
\alias{trees}
\format{A data frame with 31 observations on 3 variables.
  \tabular{rlll}{
    \code{[,1]} \tab \code{Girth} \tab numeric
    \tab Tree diameter in inches\cr
    \code{[,2]} \tab \code{Height}\tab numeric
    \tab Height in ft\cr
    \code{[,3]} \tab \code{Volume}\tab numeric
    \tab Volume of timber in cubic ft\cr}
}
\source{
  Ryan, T. A., Joiner, B. L. and Ryan, B. F. (1976)
  \emph{The Minitab Student Handbook}.
  Duxbury Press.
}
\description{
  This data set provides measurements of the girth, height and volume
  of timber in 31 felled black cherry trees.  Note that girth is the
  diameter of the tree (in inches) measured at 4 ft 6 in above the ground.
}
\references{
  Atkinson, A. C. (1985)  \emph{Plots, Transformations and Regression.}
  Oxford University Press.
}
\examples{
data(trees)
pairs(trees, panel = panel.smooth, main = "trees data")
plot(Volume ~ Girth, data = trees, log = "xy")
coplot(log(Volume) ~ log(Girth) | Height, data = trees,
       panel = panel.smooth)
summary(fm1 <- lm(log(Volume) ~ log(Girth), data = trees))
}
\keyword{datasets}
