The data below come from a comparison study of the execution times (measured in milliseconds) of five different work loads on three different configurations of a processor. The goal was to study the effect of processor configuration on computer performance. (a) Identify the experimental units, the response variable, and the two factors. (b) Calculate the ANOVA  and test whether there are differences among the three configurations. Use α = 0.05. (c) Which treatment means are significantly different from one another? Use Tukey’s multiple comparison method with α = 0.05. (d) Check the model assumptions by graphing sui plots of the residuals

(Source: R. Jain (1991), The Art of Computer Systems Performance Analysis, John Wiley & Sons, New York. Used with permission.)