A data frame with 30 observations on the following 2 variables.
batch: a factor with levels ABC
time: a numeric vector
Details
One batch of chlorine tablets (for use in home swimming pools) was suspected of having a problem. To test the batch ten tablets from that batch as well as ten tablets from each of two other batches were tested and compared.
References
Peter R. Nelson, Marie Coffin and Karen A. F. Copeland (2003), Introductory Statistics for Engineering Experimentation, Elsevier. (Appendix A)