Which of the following is not a voluntary response sample?

• A. A radio show asks listeners to call in if they have an opinion on a topic.
• B. A researcher randomly selects $50$ students from a university roster to participate in a survey.
• C. A newspaper invites readers to submit their views on a recent event.
• D. An online poll where anyone can choose to participate is conducted.

Answer: (B)

Verified step by step guidance

1. Understand the definition of a voluntary response sample: it is a sample where participants choose themselves to be part of the survey or study, often leading to bias because only those with strong opinions tend to respond.
2. Examine each option to identify if participants are self-selecting (volunteering) or if they are selected by the researcher.
3. For the radio show, listeners call in voluntarily, so this is a voluntary response sample.
4. For the newspaper, readers submit their views voluntarily, so this is also a voluntary response sample.
5. For the online poll, anyone can choose to participate, making it a voluntary response sample as well.
6. For the researcher randomly selecting 50 students from a university roster, the participants are chosen randomly by the researcher, not by self-selection, so this is NOT a voluntary response sample.