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Creating a Nonprincipal Fraction Design

By default, ADX creates the principal fraction of a fractional factorial design, meaning that the product of the coded levels of the factors in each defining contrast is 1. In some cases, however, you might want to use a nonprincipal fraction. Follow these steps:

1. Click Select Design from the main design window.
2. Select the design according to the number of factors and the number of runs you want.
3. Click Design Details and then click the Confounding Rules tab.
4. Click the down arrow to open a pop-up menu.
5. Select the fraction you want to use. Note how the confounding rules change when you select a nonprincipal fraction.
   
   

   
   
   

6. Close the window to return to the design selection window. The design you selected is still highlighted.
7. Close the window and click OK to create the design.