Chapter 9: N-Way ANOVA
You can construct ANOVA models with more than one independent variable. One of the most popular models is called a factorial model. In a factorial model, you compute variances for each independent variable as well as interaction terms. For example, if you want to investigate how race and smoking status affect a baby's birth weight, you could construct a model that looks at race (adjusted for smoking status), smoking status (adjusted for race), and each combination of race and smoking status.