Questions about whether a survey represents an entire city test selection bias: the way people enter a survey may tilt its results. Identify the target population, then ask who actually answered and whether chance picked them. A large number of responses can look convincing, but it cannot fix a recruitment method that may leave some groups underrepresented.
Hints
- Hint 1
The target population is the whole group the newspaper wants to describe. Compare all adult city residents with the people who could see this poll and chose to answer it. Are those groups guaranteed to match?
- Hint 2
In a voluntary-response sample, people decide whether to reply instead of being picked by chance. People with strong feelings about a new library may respond more often. What could that mean for a citywide estimate?
Step-by-step
Check who answered the poll
Step 1Compare the two groups
No Desmos needed. This question asks who was surveyed, not for a calculation. The target population is all adult city residents, but the sample is people who answered the newspaper’s online poll. Those groups are not necessarily alike.
- Step 2
Check how respondents were chosen
The newspaper invited readers to respond; it did not pick residents by chance. This is a self-selected sample, meaning people chose whether to join it. Readers with strong opinions may be more likely to answer, so who enters the sample matters more than how many answer.
- Step 3
Keep the conclusion within the sample
The describes the 2,300 respondents, not necessarily all adult city residents. More responses cannot remove selection bias from the way those people were recruited. The concern is that the respondents may not represent the whole city. Choice A.