SAT OwlQuestion bank / Evaluating statistical claims: observational studies and experiments
A grocery store manager wanted to know how much customers spend per visit. During one month, she recorded the amount spent by every th customer at checkout on Tuesday mornings. To which of the following groups can the results most appropriately be generalized?
All customers of the store
Customers who shop at the store on Tuesday mornings
All grocery shoppers in the store's city
Only the customers whose purchases were recorded
Show answer and explanation
Answer: B
Only customers who shopped on Tuesday mornings had a chance to be selected. Customers who shop at other times, such as weekends or evenings, may spend different amounts, so the results apply only to Tuesday morning customers.
Choice A is tempting because the manager selected customers in a regular pattern, but customers who shop at other times had no chance of being included.
Why the other choices are wrong
- A. Customers who shop at other times had no chance of being selected.
- C. Shoppers at other stores had no chance of being selected.
- D. A sample selected in a regular pattern can represent the group it was drawn from, not just itself.
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