defoam {EngrExpt}

Height of solution with defoamer

Description

The height of a solution containing a “defoamer” in a 50-ml graduated cylinder after being heated to a particular temperature.

Format

A data frame with 27 observations on the following 4 variables.

conc

concentration of defoamer - a factor with levels L < M < H

pH

pH of defoamer - a factor with levels L < M < H

temp

temperature of defoamer - a factor with levels L < M < H

height

height of solution in the graduated cylinder

Details

A defoamer is a product that controls the formation of foam in industrial processes such as one might find in the food industry.

References

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

Examples

str(defoam)
dotplot(pH ~ height|conc, defoam, groups = temp, aspect = 0.3,
        xlab = "Height of solution", type = c("p","a"),
        auto.key = list(space = "right", lines = TRUE,
                        title = "Temperature"),
        strip = FALSE, strip.left = TRUE,
        ylab = "pH within concentration")
summary(fm1 <- lm(height ~ (conc + pH + temp)^2, defoam))
summary(fm2 <- lm(height ~ (pH + temp)^3, defoam))