Clinical Trials

■■❚❙❘Chapter 11Factorial DesignZoe Fox, Dorothea Nitsch, Duolao Wang,and Ameet BakhaiIn a clinical trial, a situation may arise where the nature of thestudy calls for the evaluation of more than one treatment forsafety and/or efficacy compared to a control. Possible solutionsinclude conducting a multiple-arm parallel trial or severalseparate trials to evaluate the effect of each treatmentindividually. A more economic way to approach this problemis to conduct a factorial trial. By using a factorial design, it ispossible to evaluate individual treatment effects for more thanone treatment within the same trial. Although factorial studiesappear extremely useful on the surface, there are a numberof issues that we need to consider during their study designand analysis. In this chapter, we discuss and illustrateadvantages and problems of factorial design trials.101