PS295 Chapter 10: 10.3 Main Effects and Interactions
Document Summary
Advantage of factorial designs is that they provide info not only about separate effects of each iv but also the effects of the iv when they are combined. When we use these designs we can examine whether variability in scores was due to: (1) individual effects of each iv (2) combined or interactive effects of iv (3) error variance. The effect of a single iv in a factorial design is called a main effect. When we examine main effect of a particular iv, we pretend the other ones don"t exist and test overall effect of that iv by itself. An interaction is present when the effect of one iv differs across the levels of other iv. If one iv has a different effect at one level of another iv than it has at another level of that iv, we say the independent variables interacted.
