SAT OwlQuestion bank / Evaluating statistical claims: observational studies and experiments
To estimate the percent of adults in a town who have high-speed internet at home, a researcher emailed an online survey to adults selected at random from a list of town residents' email addresses. Of the adults who responded, reported having high-speed internet at home. Which of the following best describes the estimate of ?
It is likely too high, because adults without home internet were less likely to receive and complete an online survey.
It is likely too low, because only of the adults responded.
It is likely accurate, because the adults were selected at random.
It is likely accurate, because more than adults responded.
Show answer and explanation
Answer: A
Adults with home internet are more likely to have email and to answer an online survey. Adults without home internet are underrepresented among the respondents, so probably overstates the percent for all adults in the town.
Choice C is tempting because random selection was used, but the adults were selected only from those with email addresses, and the online format favored internet users.
Why the other choices are wrong
- B. A low response rate is a concern, but the adults most likely to be missing are those without internet, which pushes the estimate up, not down.
- C. The adults were selected only from people with email addresses, and the online format favored internet users.
- D. A large number of responses doesn't fix a biased method of collecting them.
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