computer {EngrExpt}

Repair time of computers

Description

Data from a study of the repair time for different brands of computers in different configurations.

Format

A data frame with 36 observations on the following 3 variables.

brand

a factor with levels A B C

type

an ordered factor with levels Inexpensive home < Expensive home < Business

time

time to repair computer (minutes)

References

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

Examples

str(computer)
dotplot(type ~ time, computer, groups = brand,
        auto.key = list(columns = 3, lines = TRUE),
        type = c("p","a"), jitter.y = TRUE,
        xlab = "Time to repair computer (minutes)")
summary(fm1 <- lm(time ~ brand * type, computer))
summary(fm2 <- lm(time ~ brand + type, computer))
summary(fm3 <- lm(time ~ type, computer))