You now know we consider both main effects and interactions in factorial designs. I hope that it is apparent that we also have a hypothesis (and null hypothesis) for each main effect as well as the interaction. Think about a 2 X 2 design. For this Pause Problem, first describe any study (made up or a real one) that has a 2 X 2 design (just don't use the one from your lab!), and then write out the three null hypotheses (one for Factor A, one for Factor B, and the interaction of Factors A and B!