SAT OwlQuestion bank / Evaluating statistical claims: observational studies and experiments
Researchers examined health records of randomly selected adults in a country. They found that adults who reported drinking green tea daily had a lower rate of heart disease than adults who did not. Which of the following conclusions is best supported by the study?
Drinking green tea daily causes a lower risk of heart disease for adults in the country.
Among adults in the country, drinking green tea daily is associated with a lower rate of heart disease, but it cannot be concluded that green tea causes the lower rate.
Drinking green tea daily causes a lower risk of heart disease, but only for the adults studied.
No conclusion can be drawn about adults in the country because the participants were not randomly selected.
Show answer and explanation
Answer: B
Because the adults were randomly selected from the country, the association found in the sample can be generalized to adults in the country. However, this is an observational study: the researchers did not assign who drank green tea. Other factors, such as diet or exercise, could explain the difference, so causation cannot be concluded.
Choice A ignores that without random assignment to treatment groups, an observational study cannot establish cause and effect.
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