study design factorial design factorial design factorial design is_a study design which is used to evaluate two or more factors simultaneously. The treatments are combinations of levels of the factors. The advantages of factorial designs over one-factor-at-a-time experiments is that they are more efficient and they allow interactions to be detected. In statistics, a factorial design experiment is an experiment whose design consists of two or more factors, each with discrete possible values or levels, and whose experimental units take on all possible combinations of these levels across all such factors. Such an experiment allows studying the effect of each factor on the response variable, as well as the effects of interactions between factors on the response variable. http://www.stats.gla.ac.uk/steps/glossary/anova.html#facdes And from wikipedia (01/03/2007): http://en.wikipedia.org/wiki/Factorial_experiment) pending final vetting