\Header{salinity}{Water Salinity and River Discharge}
\keyword{datasets}{salinity}
\begin{Description}\relax
The \code{salinity} data frame has 28 rows and 4 columns.


Biweekly averages of the water salinity and river discharge in Pamlico
Sound, North Carolina were recorded between the years 1972 and 1977.
The data in this set consists only of those measurements in March, April
and May.
\end{Description}
\begin{Usage}
\begin{verbatim}
data(salinity)
\end{verbatim}
\end{Usage}
\begin{Format}\relax
This data frame contains the following columns:


\describe{
\item[\code{sal}] The average salinity of the water over two weeks.

\item[\code{lag}] The average salinity of the water lagged two weeks.  Since only spring is used,
the value of \code{lag} is not always equal to the previous value of \code{sal}.

\item[\code{trend}] A factor indicating in which of the 6 biweekly periods between March and May,
the observations were taken. The levels of the factor are from 0 to 5 with
0 being the first two weeks in March.

\item[\code{dis}] The amount of river discharge during the two weeks for which \code{sal} is the
average salinity.
}
\end{Format}
\begin{Source}\relax
The data were obtained from


Ruppert, D. and Carroll, R.J. (1980) Trimmed least squares estimation in the 
linear model. 
\emph{Journal of the American Statistical Association}, \bold{75}, 828--838.
\end{Source}
\begin{References}\relax
Davison, A.C. and Hinkley, D.V. (1997) 
\emph{Bootstrap Methods and Their Application}. Cambridge University Press.
\end{References}

