ph {EngrExpt}

pH measurements in a chemical process

Description

pH measurements in a chemical process

Format

A data frame with 35 observations on the following 2 variables.

batch

a factor with levels A, B and C

ph

a numeric vector

Details

For each of three batches of material numerous pH readings were taken over the course of the production process. For this material the pH should be consistent throughout production.

References

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

Examples

str(ph)
summary(ph)
dotplot(batch ~ ph, ph, pch = 21, jitter.y = TRUE)
ph$obs <- as.integer(gl(12, 1, len = 35))
xyplot(ph ~ obs|batch, ph, type = c("g","b"), layout = c(1,3),
       strip = FALSE, strip.left = TRUE, xlab = NULL)