| % File src/library/datasets/man/warpbreaks.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2007 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{warpbreaks} |
| \docType{data} |
| \alias{warpbreaks} |
| \title{The Number of Breaks in Yarn during Weaving} |
| \description{ |
| This data set gives the number of warp breaks per loom, where a loom |
| corresponds to a fixed length of yarn. |
| } |
| \usage{warpbreaks} |
| \format{ |
| A data frame with 54 observations on 3 variables. |
| \tabular{rlll}{ |
| \code{[,1]} \tab \code{breaks} \tab numeric \tab The number of breaks\cr |
| \code{[,2]} \tab \code{wool} \tab factor \tab The type of wool (A or B)\cr |
| \code{[,3]} \tab \code{tension} \tab factor \tab 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}). |
| } |
| \source{ |
| Tippett, L. H. C. (1950) |
| \emph{Technological Applications of Statistics}. |
| Wiley. Page 106. |
| |
| } |
| \references{ |
| Tukey, J. W. (1977) |
| \emph{Exploratory Data Analysis}. |
| Addison-Wesley. |
| |
| McNeil, D. R. (1977) |
| \emph{Interactive Data Analysis}. |
| Wiley. |
| } |
| \seealso{ |
| \code{\link{xtabs}} for ways to display these data as a table. |
| } |
| \examples{ |
| require(stats); require(graphics) |
| 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) |
| } |
| \keyword{datasets} |