\HeaderA{chickwts}{Chicken Weights by Feed Type}{chickwts}
\keyword{datasets}{chickwts}
\begin{Description}\relax
An experiment was conducted to measure and compare the effectiveness
of various feed supplements on the growth rate of chickens.
\end{Description}
\begin{Usage}
\begin{verbatim}chickwts\end{verbatim}
\end{Usage}
\begin{Format}\relax
A data frame with 71 observations on 2 variables.
\describe{
\item[weight] a numeric variable giving the chick weight.
\item[feed] a factor giving the feed type.
}
\end{Format}
\begin{Details}\relax
Newly hatched chicks were randomly allocated into six groups, and each
group was given a different feed supplement.  Their weights in grams
after six weeks are given along with feed types.
\end{Details}
\begin{Source}\relax
Anonymous (1948)
\emph{Biometrika}, \bold{35}, 214.
\end{Source}
\begin{References}\relax
McNeil, D. R. (1977)
\emph{Interactive Data Analysis}.
New York: Wiley.
\end{References}
\begin{Examples}
\begin{ExampleCode}
require(stats); require(graphics)
boxplot(weight ~ feed, data = chickwts, col = "lightgray",
    varwidth = TRUE, notch = TRUE, main = "chickwt data",
    ylab = "Weight at six weeks (gm)")
anova(fm1 <- lm(weight ~ feed, data = chickwts))
opar <- par(mfrow = c(2, 2), oma = c(0, 0, 1.1, 0),
            mar = c(4.1, 4.1, 2.1, 1.1))
plot(fm1)
par(opar)
\end{ExampleCode}
\end{Examples}

