Fitting Linear Models • Loglinear Variance Models • Examining the Residuals
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Examining the Residuals
To see the dispersion effect, follow these steps:
1.
Select Help > Sample Data Library and open InjectionMolding.jmp.
2.
Select Analyze > Fit Model.
Since the variables in the data table have preselected roles assigned to them, the launch window is already filled out.
3.
Click Run.
4.
From the red triangle menu next to Loglinear Variance Fit, select Save Columns > Residuals.
5.
In the InjectionMolding.jmp sample data table, right-click on the continuous icon next to Hold Time in the Columns panel, and select Nominal.
6.
Select Analyze > Fit Y by X.
7.
Select Shrinkage Residual and click Y, Response.
8.
Select Hold Time and click X, Factor.
9.
Click OK.
Residual by Dispersion Effect
In this plot it is easy to see the variance go up as the Hold Time increases. This is done by treating Hold Time as a nominal factor.