bath {EngrExpt}

Electrical resistance after water bath

Description

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.

Format

A data frame with 4 observations on the following 3 variables.

time

time in the bath (coded as levels -1 and 1)

temp

temperature in the bath (coded as levels -1 and 1)

er

electrical resistance of the final produce (ohm/m^2)

References

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

Examples

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))