SAT OwlQuestion bank / Evaluating statistical claims: observational studies and experiments
In a study, patients with high blood pressure were randomly assigned to take either a new medication or a standard medication. What is the main purpose of randomly assigning the patients to the two groups?
To ensure that the results can be generalized to all people in the world
To guarantee that the new medication works
To increase the number of patients in the study
To make the groups similar, so that differences in results can be attributed to the medication
Show answer and explanation
Answer: D
Random assignment tends to balance other factors, such as age, diet, and health history, between the groups. Then, if the groups' results differ, the difference can reasonably be attributed to the medication. Random assignment supports cause-and-effect conclusions, not generalization to a broader population.
Choice A describes the purpose of random selection from a population, which is different from random assignment to groups.
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