I wish to find out if a new exercise program is effective in improving fitness levels among college and university students throughout south Florida. I select two schools per county in Miami-Dade, Broward, and Palm Beach counties. From each school, students age 18 to 24 may opt to take part in the exercise program which lasts for 1/2 hour, four times per week over the course of one semester. The intervention includes cardiovascular fitness, muscular fitness, stretching, relaxation, and motivation. I am aiming to recruit 200 students from each school, recruiting via flyers and word-of-mouth. I collect demographic information, weight, BMI, muscular endurance, flexibility, skin fold (body fat) measures before and after the intervention to see if there are any changes in fitness levels.

Is this a randomized controlled trial (classic experimental design)?

Why or why not?

What is the setting of this experiment?

Does this have high external validity? Internal validity? Explain.

What might be some threats to internal validity of this study?

Does this design determine causation? In other words, can I truly say that the intervention improved or did not improve fitness levels? What would you change about the study to improve my ability to determine causation?

Suggest at least two ways in which I can ensure more rigor in my study (improve internal validity).

Discuss ethical issues I should consider in my study.