In Design and Analysis of Experiments, 5th edition (John Wiley & Sons, 2001), D. C. Montgomery describes

Question:

In Design and Analysis of Experiments, 5th edition (John Wiley & Sons, 2001), D. C. Montgomery describes an experiment that determined the effect of four different types of tips in a hardness tester on the observed hardness of a metal alloy. Four specimens of the alloy were obtained, and each tip was tested once on each specimen, producing the following data:
(a) Is there any difference in hardness measurements between the tips?

b) Use Fisher€™s LSD method to investigate specific differences between the tips.
(c) Analyze the residuals from this experiment.