ABSTRACT
Experiments and quasi-experimental studies in the behavioral and social sciences often involve several independent variables that are manipulated or studied jointly. For example, an educational psychologist might be interested in the effects of both the amount of instruction (e.g., two, three, or four days a week) and the method of instruction (e.g., traditional lecture vs. hands-on learning) on the achievement of students. A factorial experiment is one in which the individual and joint effects of both of these independent variables can be studied. So, for example, an investigator might randomly assign each of 240 students to one of the conditions illustrated in Figure 7.1.
