In a survey, nonresponse bias can happen when the people who answer differ from the people who don't. Compare who was invited with who actually replied before applying the results to a larger group. Randomly selecting people to contact doesn't make the replies random. Watch for a conclusion that treats everyone contacted as though they answered.
Hints
- Hint 1
The target population is the whole group the researcher wants to describe. Here, the goal concerns town adults. The questionnaires went to households, but which households actually provided opinions?
- Hint 2
A voluntary-response sample consists of people who choose to answer. Randomly selecting households to receive a questionnaire doesn't control who sends it back. Could those who replied feel differently from those who didn't?
Step-by-step
Check who actually responded
Step 1Separate the goal from the mailing list
No Desmos needed. A calculator can't tell whether respondents represent the town. The target population is the group the researcher wants to describe: town adults. The researcher randomly selected households to receive questionnaires, so chance determined who was contacted, not whose opinion was recorded.
- Step 2
Identify who supplied the answers
Only of the contacted households returned the questionnaire. Those households chose to respond, so the answers come from a voluntary-response sample, even though the households contacted were selected at random.
- Step 3
Limit the conclusion to what the responses support
The favorable answers tell you about the respondents. People with strong feelings about bike lanes might have been more likely to reply, so the respondents might not represent all town households, let alone all town adults. Randomly choosing whom to contact doesn't randomly choose who replies. The conclusion about town adults may be unreliable. Choice B.