\Header{warpbreaks}{The Number of Breaks in Yarn during Weaving}
\keyword{datasets}{warpbreaks}
\begin{Description}\relax
This data set gives the number of warp breaks per loom, where a loom
corresponds to a fixed length of yarn.
\end{Description}
\begin{Usage}
\begin{verbatim}data(warpbreaks)\end{verbatim}
\end{Usage}
\begin{Format}\relax
A data frame with 54 observations on 3 variables.
\Tabular{rlll}{
\code{[,1]} & \code{breaks}  & numeric & The number of breaks\\
\code{[,2]} & \code{wool}    & factor  & The type of wool (A or B)\\
\code{[,3]} & \code{tension} & factor  & The level of tension (L, M, H)
}
There are measurements on 9 looms for each of the six types of warp
(\code{AL}, \code{AM}, \code{AH}, \code{BL}, \code{BM}, \code{BH}).
\end{Format}
\begin{Source}\relax
Tippett, L. H. C. (1950)
\emph{Technological Applications of Statistics}.
Wiley.  Page 106.
\end{Source}
\begin{References}\relax
Tukey, J. W. (1977)
\emph{Exploratory Data Analysis}.
Addison-Wesley.

McNeil, D. R. (1977)
\emph{Interactive Data Analysis}.
Wiley.
\end{References}
\begin{SeeAlso}\relax
\code{\Link{xtabs}} for ways to display these data as a table.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
data(warpbreaks)
summary(warpbreaks)
opar <- par(mfrow = c(1,2), oma = c(0, 0, 1.1, 0))
plot(breaks ~ tension, data = warpbreaks, col = "lightgray",
     varwidth = TRUE, subset = wool == "A", main = "Wool A")
plot(breaks ~ tension, data = warpbreaks, col = "lightgray",
     varwidth = TRUE, subset = wool == "B", main = "Wool B")
mtext("warpbreaks data", side = 3, outer = TRUE)
par(opar)
summary(fm1 <- lm(breaks ~ wool*tension, data = warpbreaks))
anova(fm1)
\end{ExampleCode}
\end{Examples}

