\Header{gravity}{Acceleration Due to Gravity}
\alias{grav}{gravity}
\keyword{datasets}{gravity}
\begin{Description}\relax
The \code{gravity} data frame has 81 rows and 2 columns.

The \code{grav} data set has 26 rows and 2 columns.

Between May 1934 and July 1935, the National Bureau of Standards in
Washington D.C. conducted a series of experiments to estimate the
acceleration due to gravity, \emph{g}, at Washington.  Each experiment
produced a number of replicate estimates of \emph{g} using the same
methodology.  Although the basic method remained the same for all
experiments, that of the reversible pendulum, there were changes in
configuration.

The \code{gravity} data frame contains the data from all eight
experiments.  The \code{grav} data frame contains the data from the
experiments 7 and 8.  The data are expressed as deviations from 980.000
in centimetres per second squared.
\end{Description}
\begin{Usage}
\begin{verbatim}
data(gravity)
\end{verbatim}
\end{Usage}
\begin{Format}\relax
This data frame contains the following columns:

\describe{
\item[\code{g}] The deviation of the estimate from 980.000 centimetres per second squared.

\item[\code{series}] A factor describing from which experiment the estimate was derived.
}
\end{Format}
\begin{Source}\relax
The data were obtained from

Cressie, N. (1982) Playing safe with misweighted means. 
\emph{Journal of the American Statistical Association}, \bold{77}, 754--759.
\end{Source}
\begin{References}\relax
Davison, A.C. and Hinkley, D.V. (1997) 
\emph{Bootstrap Methods and Their Application}. Cambridge University Press.
\end{References}

