| bath {EngrExpt} | R Documentation |
In a production process a rubber material is extruded in a continous ribbon (about 2 feet in width). In one step of the process the product passes through a water bath. In this experiment the time spent in the bath and the temperature of the bath were varied to determine their effect on the electrical resistance of the final product.
A data frame with 4 observations on the following 3 variables.
timetemperPeter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)
str(bath)
dotplot(ordered(time) ~ er, bath, groups = temp, type = c("p","a"),
xlab = expression("Electrical resistance (ohm/" * m^2 * ")"),
ylab = "Time in bath (coded)",
auto.key = list(columns = 2, lines = TRUE))
summary(fm1 <- lm(er ~ time * temp, bath))
summary(fm2 <- lm(er ~ time + temp, bath))
summary(fm3 <- lm(er ~ temp, bath))