Imagine you are driving down the street, when the car in front of you stops suddenly. Who taught you how to drive? Driving skill or lack thereof is not the only possible explanation for the other driver's behavior. If he was avoiding a road hazard, or if a dog ran out in front of his car, you would not assume that the driver is unfit to be on the road. At other times, the rationale for a person's behavior is not easy to determine. Suppose that your neighbor Mary mentioned that her husband John has been putting in long hours at work and is too exhausted to do much on the weekends. You might attribute this change in behavior to his recent promotion. Several weeks ago, however, you saw John entering a fancy restaurant with his arm around a woman you didn't recognize. Questions raced through your mind. Who is she? What is he doing with her? Could he be having an affair? Mary also confided that John sometimes gets up in the middle of the night to talk on the phone and surf the internet. You might interpret this as more evidence of an affair, and wonder if Mary suspects it too. Your observations are forming a pattern that indicates infidelity, but they are not proof. Your suspicions are confirmed when Mary throws John out of the house and calls you to comfort her regarding his cheating behavior. Such an event might lead you to ponder a larger question-- in this case, what causes marital infidelity? Finding the answer to such a question is challenging. How do you separate opinion from valid fact? And how do you ensure that the results of your research are valid? In this course, you learn how to consider answers to these and other research questions. You will apply scientific research methods to translate your hunches into hypotheses that can be tested and measured.