Modeling and Multivariate Methods - SAS

236 Analyzing Screening Designs Chapter 8
Additional Examples
Analyzing a Plackett-Burman Design
Plackett-Burman designs are an alternative to fractional-factorial screening designs. Two-level fractional
factorial designs must, by their nature, have a number of runs that are a power of two. Plackett-Burman
designs exist for 12-, 24-, and 28-run designs.
Weld-Repaired Castings.jmp from the Sample Data folder uses a Plackett-Burman design, and is found in
textbooks such as Giesbrecht and Gumpertz (2004) and Box, Hunter, and Hunter (2005). Seven factors are
thought to be influential on weld quality. The seven factors include Initial Structure, Bead Size, Pressure
Treatment, Heat Treatment, Cooling Rate, Polish, and Final Treatment. A Plackett-Burman design with 12
runs is used to investigate the importance of the seven factors. The response is 100 × log( lifetime)
. (There
are also four terms that were used to model error that are not used in this analysis.)
Using the Screening platform, select the seven effects as X and Log Life as Y. (If terms are automatically
populated in the Screening Platform launch window, remove the four error terms listed as effects.) Click
OK. Figure 8.5 appears, showing only a single significant effect.
Figure 8.5 Screening Report for Weld-Repaired Castings.jmp