SAT OwlQuestion bank / Evaluating statistical claims: observational studies and experiments
A study of randomly selected families in a city found that children in homes with more books tended to have higher reading test scores. Which of the following statements is best supported by this study?
Increasing the number of books in a home will cause a child's reading scores to rise.
Higher reading scores cause families to buy more books.
The number of books in a home has no relationship with reading scores in the city.
In the city, the number of books in a home is positively associated with children's reading scores.
Show answer and explanation
Answer: D
This is an observational study, because the researchers did not assign how many books each home had. It shows an association, and because the families were randomly selected, the association can be generalized to families in the city. It can't show causation; other factors, such as parents' education, could affect both variables.
Choice A claims cause and effect, which an observational study with no random assignment cannot establish.
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