In the following example from Atkinson and Donev (1992), you create a design for an experiment involving both mixture factors and process factors. The design is an 18-run design that is balanced with respect to the levels of a categorical factor. The design enables you to fit a full response surface. You use Design Evaluation plots and results to examine the relative prediction variance of the design.
The response is Damping, which measures the electromagnetic damping of an acrylonitrile powder.
CuSO4 (copper sulphate), ranging from 0.2 to 0.8
Na2S2O3 (sodium thiosulphate), ranging from 0.2 to 0.8
Glyoxal (glyoxal), ranging from 0 to 0.6
The nonmixture environmental factor of interest is Wavelength (the wavelength of an electromagnetic wave) at three levels denoted L1, L2, and L3.
Wavelength is a continuous variable. However, the researchers were interested only in predictions at three specific wavelengths. For this reason, you treat Wavelength as a categorical factor with three levels.
1.
Select DOE > Custom Design.
2.
Double-click Y under Response Name and type Damping.
3.
Click Maximize under Goal and change it to None.
The goal is set to None because the authors of the study do not mention how much damping is desirable.Select Help > Sample Data Library and open Design Experiment/Donev Mixture Factors.jmp.
Figure 4.52 Responses Outline and Factors Outline
5.
In the Model outline, click Interactions > 2nd.
6.
Click OK to dismiss the message.
Figure 4.53 Model and Design Generation Outlines
Note: Setting the Random Seed in step 8 and Number of Starts in step 9 reproduces the exact results shown in this example. In constructing a design on your own, these steps are not necessary.
8.
(Optional) From the Custom Design red triangle menu, select Set Random Seed, type 858576648, and click OK.
9.
(Optional) From the Custom Design red triangle menu, select Number of Starts, type 10, and click OK.
10.
Click Make Design.
Figure 4.54 Design Outline Showing 18-Run Design
1.
Open the Design Evaluation > Prediction Variance Profile outline.
Figure 4.55 Prediction Variance Profile for 18-Run Design
Move the slider for Wavelength to verify that the relative prediction variance profiles for the mixture factors do not change across the levels of Wavelength. Move the slider for any one of the mixture factors. The sliders for the other two mixture factors adjust to make the mixture ingredients sum to one. Notice that the smallest relative prediction variances occur near the center settings for the mixture factors.
3.
Open the Fraction of Design Space Plot outline.
Figure 4.56 Fraction of Design Space Plot for 18-Run Design
4.
Open the Design Diagnostics outline.
Figure 4.57 Design Diagnostics Outline for 18-Run Design

Help created on 7/12/2018