adhesion dataset

Adhesive qualities of a lens coating

These data are from two experiments to examine the effect of formulation changes on the adhesive properties of a eye glass lens coating. If the coating would not adhere to the lens surface then the formulation would not be marketable. The first experiment (adhesion) considered only pH (i.e., one factor). In this experiemnt three formulations were made (one at each of three pH levles) and ten samples from each formulation were tested. The test procedure for measuring adhesion is known to contain a large amount of test error. In the second experiment ( adhesion2 the effect of pH (3 levels) and a catalyst (2 levels) were tested. The data consists of five samples were taken from and tested from each of the six formulations. 1.1

data

Format

adhesion is a data frame with 30 observations on the following 2 variables.

• adhesion: a numeric vector
• pH: a numeric vector at three distinct levels

adhesion2 is a data frame with 30 observations on the following 3 variables.

• cat: a factor with levels A and B
• pH: a numeric vector
• adhesion: a numeric vector

References

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

Examples

str(adhesion)
xtabs(~ pH, adhesion)
xyplot(adhesion ~ pH, adhesion,
       ylab = "Adhesion of a lens coating", xlab = "pH",
       type = c("g", "p", "a"))
dotplot(as.factor(pH) ~ adhesion, adhesion, ylab = "pH",
        type = c("p","a"), xlab = "Adhesion of a lens coating")
str(adhesion2)
xtabs(~ cat + pH, adhesion2)
dotplot(as.factor(pH) ~ adhesion, adhesion2, groups = cat,
        type = c("p","a"), ylab = "pH",
        auto.key = list(space = "right", lines = TRUE,
                        title = "Catalyst"))