To judge a survey, compare its target population, the people the researcher wants to describe, with the people who could actually answer. A survey placed near something connected to its topic may have selection bias: that location can favor one opinion. Even many positive responses describe the respondents, not necessarily everyone the researcher hoped to study.
Hints
- Hint 1
Identify the target population, the whole group the principal wants to describe. Is that group the students who chose to write comments, or all the students whose opinions the principal wants?
- Hint 2
Look at where the box was placed. Students near a salad bar may have different food preferences from students elsewhere. Would their comments represent everyone at school?
- Hint 3
In a voluntary-response sample, people choose whether to take part. Even with many responses, could that choice and the box’s location affect which opinions get counted?
Step-by-step
Check who could respond
Step 1Identify the group the principal wants to describe
No Desmos needed. The question is about how students were chosen, not a calculation. The principal wants to know how students feel about the menu, so the target population, the whole group to describe, is all students in the school.
- Step 2
Find who actually responded
The box was next to the salad bar, and students chose to leave comments. This is a voluntary-response sample: students decided for themselves whether to answer. So the comments didn’t come from a random selection of all students.
- Step 3
Check whether the location favors an opinion
Students who use the salad bar may already favor healthy food, so the positive comments don’t show that most students across the school feel that way. This is selection bias: the way students enter the sample can favor one opinion. More comments from a biased source don’t fix the bias. The principal’s salad-bar method is biased. Choice B.