Cake data (Data file: cakes) Fit XXXXXXXXXXand verify that the significance levels for the quadratic terms and the interaction are all less than XXXXXXXXXXWhen fitting polynomials, tests concerning...

Cake data (Data file: cakes)

Fit (5.12) and verify that the significance levels for the quadratic terms and the interaction are all less than 0.005. When fitting polynomials, tests concerning main effects in models that include a quadratic are generally not of much interest.

The cake experiment was carried out in two blocks of seven observations each. It is possible that the response might differ by block. For example, if the blocks were different days, then differences in air temperature or humidity when the cakes were mixed might have some effect on Y. We can allow for block effects by adding a factor for block to the mean function and possibly allowing for block by regressor interactions. Add block effects to the mean function fit in Section 5.3.1 and summarize results. The blocking is indicated by the variable Block in the data file.