Factor Changes

The Factor Changes column property indicates how difficult it is to change factor settings in a designed experiment. The possible specifications for Factor Changes are Easy, Hard, and Very Hard. For example, Factor Changes Column Property Panel shows the Factor Changes column property panel for the factor A1 in the Battery Data.jmp sample data table, located in the Design Experiment folder.

Factor Changes Column Property Panel

•	When a design contains factors that are hard-to-change and very-hard-to-change, it must also include a subplot and a whole plot factor:

‒	The levels of the whole plot factor define the groups of runs for which the levels of the very-hard-to-change factors are held constant.

‒	The levels of the subplot factor define the groups of runs for which the levels of the hard-to-change factors are held constant.

•

When a design contains only factors that are hard-to-change, but no factors that are very-hard-to-change, it should include a whole plot factor. The levels of the whole plot factor define the groups of runs for which the levels of the hard-to-change factors are held constant. For more details, see Changes and Random Blocks in Custom Designs.

Augment and Evaluate Design

For the Evaluate Design and Augment Design platforms, the Factor Changes column property identifies factors with Changes specified as Hard or Very Hard. However, these platforms also require that the whole plot and subplot factors be entered as model effects in the launch windows. This is because the whole plot and subplot factors are part of the design structure.

Custom Design

The Custom Design platform enables you to create designs where all factor changes are Easy. You can also construct split-plot, split-split plot, or two-way split-plot (strip-plot) designs. When constructing these designs, you need to identify the factors whose values are hard-to-change or very-hard-to-change. In the Factors outline, you can identify factors as having Changes that are Easy, Hard, or Very Hard. When the Custom Design platform constructs the design table, the Factor Changes property is assigned to every factor that appears in the Factors outline.

The Custom Design platform is the only platform that constructs designs for factors with Changes that are Hard or Very Hard. Other DOE platforms also assign the Factor Changes column property to factors that they construct, but the value of the column property is set to Easy for their factors.

If you Load Factors in the Custom Design window using a table of factors, you can assign the Factor Changes column property to columns in that table. When you Load Factors using that table, your Factor Changes specifications appear in the Factors outline.

Factor Changes Example

The Battery Data.jmp sample data table, found in the Design Experiment folder, contains data from an experiment that studies the open current voltage of batteries (OCV). The design is a two-way split-plot design. For further background, see Examples of Custom Designs section.

1.	Select Help > Sample Data Library and open Design Experiment/Battery Data.jmp.

2.	Click the asterisk to the right of the factor C1 in the columns panel.

3.	Select Factor Changes.

Factor Changes Panel for C1

The value of Factor Changes for C1 is Hard. Factor Changes Column Property Panel shows that the value of Factor Changes for A1 is Very Hard.

Click OK.

5.	In the data table, click the red triangle next to DOE Dialog and select Run Script.

6.	Open the Factors outline.

Factors Outline for Battery Experiment

The factors A1, A2, A3, and A4 have Changes set to Very Hard, and the factors C1 and C2 have Changes set to Hard. When the Custom Design platform constructs the design table, it saves these specifications to the appropriate columns as Factor Changes column properties.

In the Design outline, notice the Whole Plots and Subplots factors.

Design Outline Partial View

To account for the factor changes that are Hard and Very Hard, two factors are created by the Custom Design platform. The Whole Plots factor groups the runs where the Very Hard factor levels are constant and the Subplots factor groups the runs where the Hard factors levels are constant. These factors need to be included as model effects when you enter columns with the Factor Changes column property in the Evaluate Design and Augment Design platforms.