Passage Summary: A group sent out 5,000 letters and got 300 back. Because almost everyone who replied liked them, they assume almost everyone they mailed likes them.

Conclusion: The majority of the 5,000 people who received the letter likely agree with the organization's social position.

Reasoning: Out of the 300 people who chose to respond to the survey, the vast majority (283) expressed agreement with the organization.

Analysis: This is a textbook case of a 'self-selection bias' or an unrepresentative sample. People who take the time to respond to a fund-raising survey from a specific advocacy group are significantly more likely to support that group than those who ignore the letter. The 300 respondents are not a random cross-section of the 5,000 recipients. Look for an answer that highlights how the people who responded might differ fundamentally from the people who didn't.