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Modeling and Multivariate Methods - SAS

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Chapter 8 Analyzing Screening Designs 237<br />

Additional Examples<br />

Note asterisks mark four terms, indicating that they are not orthogonal to effects preceding them, <strong>and</strong> the<br />

obtained contrast value was after orthogonalization. So, they would not match corresponding regression<br />

estimates.<br />

Analyzing a Supersaturated Design<br />

Supersaturated designs have more factors than runs. The objective is to determine which effects are active.<br />

They rely heavily on effect sparsity for their analysis, so the Screening platform is ideal for their analysis.<br />

As an example, look at Supersaturated.jmp, from the Sample Data folder, a simulated data set with 18<br />

factors but only 12 runs. Y is generated by<br />

Y = 2( X7) + 5( X10) – 3( X15)<br />

+ ε<br />

where ε ~ N(0,1). So, Y has been constructed with three active factors.<br />

To detect the active factors, run the Screening platform with X1–X18 as X <strong>and</strong> Y as Y. The report shown in<br />

Figure 8.6 appears.<br />

Figure 8.6 Screening Report for Supersaturated.jmp

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