Which of the following scenarios best exemplifies a multiple-baseline design?

A. Ewa is an athletic trainer at the university. She conducts research on violence in sport. She has designed a study to examine the effects of a new sportsmanship class. She randomly assigns teams by sport to be in either her new class or not. That is, some teams are in the class and others are not. She then compares incidents of violence between groups.

B. Laura has developed a new treatment to increase spatial ability. She randomly assigns students to either her intervention or a control condition. In the treatment condition students engage in working puzzles for twenty minutes a day for 10 days. Unfortunately, students don't like her intervention and refuse to do puzzles for all of the days.

C. Bryce is an occupational therapist working with Sandy, a brain-injured patient. Bryce has decided to test the effects of a graphing strategy with Sandy. He starts the graphing technique, while collecting data in the form of minutes of strength training per day. He discontinues the graphing technique still collecting minutes of strength training per day. Bryce then reintroduces the graphing technique.

D. Mr. Matthews, the school psychologist, is called by the third-grade teacher because one of the students, Seamus, has been referred for a new behavioral intervention plan, in which the teacher uses nonverbal signals as a positive consequence when Seamus engages in appropriate behavior. Mr. Matthews observes Seamus's behavior in the regular classroom and in Art and Music class. He records off-task behavior, calling out, and touching others for eight days.