Using Stepwise Regression to Find Possible Interactions in a Non-interaction Model DOE
Jed Campbell, US Synthetic Corporation
Because traditional screening DOEs cannot resolve interactions, avoiding their use is important. Sometimes, however, they can’t be avoided. This presents a problem when an interaction is suspected: often a budget for experimental runs has been used up, the window of opportunity for experimentation has passed, or augmentation of the design is not possible. Also, trying to force-fit an interaction model runs toward degrees-of-freedom problems and often causes software to complain. JMP provides a method for discovery of potential interactions in a DOE that doesn’t (by design) allow for interactions. Using the Stepwise personality in the Fit Model platform highlights potential interactions in a non-interaction model DOE.
