We will begin with the simplest factorial design -- 2 x 2 ANOVA. In this design, we have two independent variables, each with two levels/groups in the study design. Remember that we describe each factor in our design by the number of levels or groups in the design.

We are examining the results of a study of eye-witness testimony. The investigators wish to know whether recall of important information is influenced by the severity of the crime and the amount of time that passes before the witness is asked to recall important events. The study is described below.

The first independent variable is severity of the crime. A videotape is made of a man stealing a woman's purse in an uncrowded clothing store. A second videotape is made, using the same actors, of a man using a gun to rob the cash register of the same clothing store. In this scenario, the woman is a sales clerk behind the cash register and there are two people standing at the counter.