Two- and three-way factorial ANOVA
This chapter discusses one-way ANOVA which focuses on two or more independent variables. The use of factorial ANOVA is perhaps one of the most common statistical procedures used to analyze data in kinesiology/exercise science. The types of research questions answered with two-way factorial ANOVA are those which examine the interaction between training and supplementation, or gender and age, on a dependent variable. The assumptions of factorial ANOVA are similar to those applied in one-way ANOVA, and are applied to the independent variables and interaction cells on the dependent variable. Although generally robust to assumption violations, factorial ANOVA results are susceptible to bias especially when group sizes are disparate with unequal variances. The three-way ANOVA extends the two-way ANOVA by adding another factor to help explain the dependent variable. In three-way ANOVAs, main effects are produced, as are two-way interactions, and three-way interactions.