View all three predictors as factors with three levels, and without transforming cycles, fit the second-order mean function with regressors for all main effects and all two-factor interactions....

View all three predictors as factors with three levels, and without transforming cycles, fit the second-order mean function with regressors for all main effects and all two-factor interactions. Summarize results of the amp by load interaction with an effects plot.

Fit the first-order mean function consisting only of the main effects. From Problem 8.6.2, this mean function is not adequate for these data based on using cycles as the response because the tests for each of the two-factor interactions indicate that these are likely to be nonzero. Use the Box–Cox method to select a transformation for cycles based on the first-order mean function.