Description Format References Examples
Drying times of different concrete mixes used in a sidewalk. Mix
‘A
’ is the conventional mix. Mixes ‘B
’
and ‘C
’ are experimental, and more expensive, mixes.
A data frame with 19 observations on the following 2 variables.
type
concrete mix - a factor with levels A
,
B
and C
time
time (hr) until concrete is dry enough to walk on
Peter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | str(cement)
dotplot(reorder(type, time) ~ time, cement, type = c("p","a"),
jitter.y = TRUE, ylab = "Mix type",
xlab = "Time until concrete is dry enough to walk on (hours)")
qqmath(~ time, cement, groups = type, aspect = 'xy',
xlab = "Standard normal quantiles",
type = c("g","p"),
panel=function(...)
{
panel.qqmathline(..., alpha = 0.5, lty = 2)
panel.qqmath(...)
},
ylab = "Time until concrete is dry enough to walk on (hours)",
auto.key = list(space = "right", title = "Type", lines = TRUE))
summary(fm1 <- aov(time ~ type, cement))
TukeyHSD(fm1)
|
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