Design & Factor Selection
Design Types & Categories
Casual Factors ( Random Variable or Covariate) - Occasionally, an experimental factor will be present that is not controllable for an experimental run. Such a factor cannot be included in a design, but can be recorded and included in the experimental data, for example, outside air temperature, run sequence, and day of the week. A poor fit of the data to the model is sometimes an indicator of the presence of a significant casual factor.
Learn more about the DOE tools for designed experiments in Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller, in his online Intro. to DOE short course (only $99) or online Advanced Topics in DOE short course (only $139), or his online Black Belt certification training course ($875).