Question 40·Easy·Evaluate Statistical Claims: Observational Studies and Experiments
A retailer emailed 500 customers who had made at least one online purchase from the retailer in the past month. The customers were asked whether they would use a curbside pickup option if it were offered, and 70% responded that they would use it.
Which of the following conclusions is best supported by the survey results?
For survey and experiment questions, first lock in three things: who was studied (the population), what was measured (the variable, like a preference or behavior), and how it was done (survey vs. experiment). Then, eliminate any answer that (1) changes the group to people who were never studied, (2) changes the outcome to something that was not measured, or (3) makes a cause-and-effect claim when there was only an observational survey. The correct choice will stay strictly within the population and question described in the prompt.
Hints
Focus on the group in the description
Underline the part of the prompt that tells you who the 500 customers are. Any valid conclusion has to be about that same kind of person.
Focus on what was actually asked
What exact question did the email ask the customers? A good conclusion should involve that same behavior or opinion, not something different like spending habits.
Watch out for changing the population
For each answer choice, ask: Is it still talking about customers like the ones surveyed, or does it suddenly talk about all shoppers or people who were never surveyed?
Watch out for cause-and-effect claims
Did the retailer actually run an experiment comparing groups, or did they just ask a question? If there was no experiment, you cannot conclude that one thing will cause another (like causing people to spend more).
Step-by-step Explanation
Identify who was surveyed
Carefully read the description of the survey. The retailer emailed 500 customers who had made at least one online purchase from the retailer in the past month. That is the group (population) the survey information can reasonably describe.
Identify what was measured
The survey asked these customers whether they would use a curbside pickup option if it were offered, and 70% responded that they would use it. So the data tell us about the proportion of these online customers who say they would use curbside pickup.
Understand the limits of the conclusion
From a survey, you can usually describe the same type of people who were surveyed and the same behavior/opinion that was asked about. You cannot:
- Jump to a completely different group (like all shoppers nationwide or people who never shop online).
- Claim cause-and-effect (like saying a new option will make people spend more) unless there was a controlled experiment, which is not described here.
Match the supported conclusion to the choices
Look for the option that:
- Refers to customers who made at least one online purchase at the retailer last month (the group surveyed), and
- Talks about whether they would use curbside pickup (what was measured), without making any extra assumptions about other groups or about spending behavior. The only choice that fits these limits is: “About 70% of customers who made at least one online purchase at the retailer last month would use curbside pickup.”