Example Using Loglinear Variance

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Fitting Linear Models • Loglinear Variance Models • Example Using Loglinear Variance

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The data table InjectionMolding.jmp contains the experimental results from a 7-factor 27-3 fractional factorial design with four added centerpoints (Montgomery 1991). Preliminary investigation determined that the mean response only seemed to vary with the first two factors, Mold Temperature, and Screw Speed, and the variance seemed to be affected by Holding Time.

Figure 9.1 Injection Molding Data

Select Help > Sample Data Library and open InjectionMolding.jmp.

Select Analyze > Fit Model.

Since the variables in the data table have been assigned preselected roles, the launch window is already filled out.

Figure 9.2 Fit Model Dialog

Click Run.

Figure 9.3 Loglinear Variance Report Window

The Mean Model for Shrinkage report gives the parameters for the mean model, and the Variance Model for Shrinkage report gives the parameters for the variance model.

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Help created on 10/11/2018