Scenario Doctors in a maternity ward study whether the brand of diaper worn by a baby and the type of background music played in the nursery affect the amount of time that babies cry. They put 20 boy babies in Huggies and 20 girl babies in Luvs. Each day (for 4 days) they play classical music from midnight to 8 AM, rock music from 8 AM to 4 PM, and jazz from 4 PM to midnight. They find that babies in Huggies cry more total minutes than babies in Luvs. They also find that babies cry more total minutes while jazz music is playing than while rock music is playing, and that babies cry more when rock music is playing than when classical music is playing. They conclude that the type of music affects how much time babies cry. Question at position 8 8 Multiple Choice 3 points Question at position 8 What kind of design are the doctors using? What kind of design are the doctors using? Retrospective ex post facto because the babies cry after they are already in the diapers 2 X 3 mixed-subjects factorial design Cross-sectional developmental study with gender being the cross-sectional variable Interrupted time series because the type of music changes across hours of the day 2 X 3 within-subjects factorial design