\Header{Orthodont}{Growth curve data on an orthdontic measurement}
\keyword{datasets}{Orthodont}
\begin{Description}\relax
The \code{Orthodont} data frame has 108 rows and 4 columns of the
change in an orthdontic measurement over time for several young subjects.
\end{Description}
\begin{Format}\relax
This data frame contains the following columns:
\describe{
\item[distance] a numeric vector of distances from the pituitary to the
pterygomaxillary fissure (mm).  These distances are measured
on x-ray images of the skull.

\item[age] a numeric vector of ages of the subject (yr).

\item[Subject] an ordered factor indicating the subject on which the
measurement was made.  The levels are labelled \code{M01}
to \code{M16} for the males and \code{F01} to \code{F13} for
the females.  The ordering is by increasing average distance
within sex.

\item[Sex] a factor with levels
\code{Male} and
\code{Female} 

}
\end{Format}
\begin{Details}\relax
Investigators at the University of North Carolina Dental School
followed the growth of 27 children (16 males, 11 females) from age 8
until age 14.  Every two years they measured the distance between the
pituitary and the pterygomaxillary fissure, two points that are easily
identified on x-ray exposures of the side of the head.
\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.17)

Potthoff, R. F. and Roy,  S. N. (1964), ``A generalized multivariate
analysis of variance model useful especially for growth curve
problems'', \emph{Biometrika}, \bold{51}, 313--326.
\end{Source}
\begin{Examples}
\begin{ExampleCode}
data(Orthodont)
formula(Orthodont)
plot(Orthodont)
\end{ExampleCode}
\end{Examples}

