

   warpbreaks {base}                            R Documentation

   TThhee NNuummbbeerr ooff BBrreeaakkss iinn YYaarrnn dduurriinngg WWeeaavviinngg

   DDeessccrriippttiioonn::

        This data set gives the number of warp breaks per loom,
        where a loom corresponds to a fixed length of yarn.

   UUssaaggee::

        data(warpbreaks)

   FFoorrmmaatt::

        A data frame with 54 observations on 3 variables.

         [,1]      breaks       numeric      The number of breaks
         [,2]      wool         factor       The type of wool (A or B)
         [,3]      tension      factor       The level of tension (L, M, H)

   SSoouurrccee::

        L. H. C. Tippet (1950).  Technological Applications of
        Statistics, Wiley, page 106.

   RReeffeerreenncceess::

        Tukey, J. W. (1977).  Exploratory Data Analysis.  Addi-
        son-Wesley.  McNeil, D. (1977).  Interactive Data Anal-
        ysis.  Wiley.

   EExxaammpplleess::

        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)

