Specify whether to use a non-hierarchical model for Select Optimal Design

Use to allow Minitab to add the displayed terms to the model in order to create a hierarchical model. In a hierarchical model, all lower-order terms that comprise the higher-order terms also appear in the model. For example, a model that includes the interaction term A*B*C must also include the terms: A, B, C, A*B, A*C, and B*C to be hierarchical.

Usually, you select, improve, and augment designs with a hierarchical model so that you can produce an equation in uncoded (or natural) units. An optimal design that you produce from a non-hierarchical model might not have all the experimental runs to fit a hierarchical model. However, you can evaluate the D-optimality of a non-hierarchical model.

Would you like Minitab to make your model hierarchical?

Specify whether Minitab adds terms to the model.

• Add terms to make the model hierarchical (recommended): Minitab will add the displayed terms to produce a hierarchical model.
• Use the specified non-hierarchical model: Minitab will not add the terms.

Use this choice from now on

Select to make your choice the default. You will skip this dialog in the future. If you check this option, you can change the setting in File > Options > Linear Models > Model Hierarchy.