In a study of U.S. high school students' physical activity, the sample is drawn from a list of students on sports teams at a local high school. What is the group from which the sample is drawn?

• A. All high school students in the United States.
• B. All the students at this high school who engage in physical activity.
• C. All students enrolled at this high school.
• D. Students at the local high school who are on the sports teams.

Answer: (D)

The main idea here is identifying the sampling frame—the actual group from which participants are drawn. In this study, researchers use a list of students on sports teams at a local high school as the source for selecting participants. So the group the sample is drawn from is the students at that high school who are on the sports teams. This is narrower than all high school students in the United States and narrower than all students at the high school (which would include non‑athletes), but it exactly matches the described source. Understanding this helps you see that the study’s findings will pertain to that sports‑team subgroup and may not generalize to all students or to students nationwide.