28.2 Analysis of the Results
Stat > DOE > Response Surface > Analyze Response Surface Design
Selecting one of the options of the dropdown box, all those terms that correspond to the chosen option are placed in the list of Selected Terms. The central buttons with arrows can be used to move specific terms from the list of Available Terms to the list of Selected Terms for the model, or vice versa.
Start out with the full model (Full quadratic). The Minitab output has been divided in parts to ease the interpretation of it.
In the previous analysis of variance table a very large p-value (0.794) is reported for the interactions hypothesis test. This means that the null hypothesis (interactions are null) cannot be rejected and we proceed to remove them from the model.
Both the linear term rpm and the quadratic term rpm × rpm are not significant and are removed from the model: