EngrExpt: cement – R documentation

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cement

Drying times of concrete

Description

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.

Format

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

References

Peter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)

Examples

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)

EngrExpt

Data sets from "Introductory Statistics for Engineering Experimentation"

v0.1-8

GPL (>= 2)

Authors

R port by Douglas Bates <bates@stat.wisc.edu> and Karen A.F. Copeland <karen@boulderstats.com>

Initial release

2009-08-21