Screening Designs
Screening designs are among the most popular designs for industrial experimentation. Typically used in the initial stages of experimentation, they examine many factors in order to identify those factors that have the greatest effect on the response. The factors that are identified are then studied using more sensitive designs. Because screening designs generally require fewer experimental runs than other designs, they are a relatively inexpensive and efficient way to begin improving a process.
If a standard screening design exists for your experimental situation, you can choose from several standard screening designs. The list includes blocked designs when applicable. Your factors can be two-level continuous factors, three-level categorical factors, or continuous factors that can assume only discrete values (discrete numeric factors).
However, there are situations where standard screening designs are not available. In these cases, the Screening Design platform constructs a main effects screening design. A main effects screening design is either orthogonal or near orthogonal. It focuses on estimating main effects in the presence of negligible interactions.
Note that JMP also provides two compelling alternatives to screening designs:
• Definitive screening designs are particularly useful if you suspect active two-factor interactions or if you suspect that a plot of a continuous factor’s effect on the response might exhibit strong curvature. See Definitive Screening Designs.
• Custom designs are highly flexible and often more cost-effective than a design obtained using alternative methods. See Custom Designs.
Figure 9.1 Results from a Fractional Factorial Design
