warpbreaks | R Documentation |
This data set gives the number of warp breaks per loom, where a loom corresponds to a fixed length of yarn.
warpbreaks
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) |
There are measurements on 9 looms for each of the six types of warp
(AL
, AM
, AH
, BL
, BM
, BH
).
Tippett, L. H. C. (1950) Technological Applications of Statistics. Wiley. Page 106.
Tukey, J. W. (1977) Exploratory Data Analysis. Addison-Wesley.
McNeil, D. R. (1977) Interactive Data Analysis. Wiley.
xtabs
for ways to display these data as a table.
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)