While researching a topic, a student has taken the following notes:
<ul> <li>Two studies measured the effect of after-school programs on math performance.</li> <li>Study A randomly assigned 200 students to programs or controls.</li> <li>Study B compared students who voluntarily enrolled with those who did not, with a sample of 5,000.</li> <li>Study A reported a moderate effect with high internal validity.</li> <li>Study B reported a larger effect but might confound motivation with the program's impact.</li> </ul> The student wants to emphasize that the larger Study B's results may not be straightforward to interpret. Which choice most effectively uses relevant information from the notes to accomplish this goal?Which choice most effectively makes the student's point?
- A
Study A randomly assigned 200 students.
- Bcheck_circle
Although Study B's larger sample reported a bigger effect, its voluntary enrollment design may confound students' motivation with the program's actual impact.
- C
Both studies measured math performance.
- D
Study A reported a moderate effect.
Explanation
The goal is interpretive caution about Study B. Choice B names the larger effect and the confound. The others address Study A or describe both methods.