\HeaderA{Spruce}{Growth of Spruce Trees}{Spruce}
\keyword{datasets}{Spruce}
\begin{Description}\relax
The \code{Spruce} data frame has 1027 rows and 4 columns.
\end{Description}
\begin{Format}\relax
This data frame contains the following columns:
\describe{
\item[Tree] a factor giving a unique identifier for each tree.

\item[days] a numeric vector giving the number of days since the
beginning of the experiment.

\item[logSize] a numeric vector giving the logarithm of an estimate of the
volume of the tree trunk.

\item[plot] a factor identifying the plot in which the tree was grown.

}
\end{Format}
\begin{Details}\relax
Diggle, Liang, and Zeger (1994, Example 1.3, page 5)
describe data on the growth of spruce trees that have been exposed to
an ozone-rich atmosphere or to a normal atmosphere.
\end{Details}
\begin{Source}\relax
Pinheiro, J. C. and Bates, D. M. (2000), \emph{Mixed-Effects Models in S
and S-PLUS}, Springer, New York.  (Appendix A.28)

Diggle, Peter J., Liang, Kung-Yee and Zeger, Scott L. (1994),
\emph{Analysis of longitudinal data}, Oxford University Press,
Oxford.
\end{Source}

