ABSTRACT
In this chapter, we study linear models for two and three factors, also known as two-way and three-way analysis of variance models, respectively.
6.1.1 I n t r o d u c t i o n
In Chapter 3 we analyzed the one-factor linear model, in which the main question is the comparison of groups of observations in terms of their means. We now turn to the case of models with two factors, in which a new ques tion arises, namely tha t of interaction between factors. We have already studied the question of interaction between two continuous variables in con nection with the response surface model of Section 4.4.3. A further issue in connection with the factor models is the notion of a balanced experiment, and the simplification of the analysis tha t derives from the balance.
