Here is something you don't get to see every day. I thought I'd post it for reference.
This is the actual letter that Arbitron sends out to sampled households.You may notice some vague dark smearing in the center of the letter. That is not a bad scan. that is a mark from the fresh, crisp one dollar bill that was enclosed. This letter is from one of my neighbors, I borrowed, scanned and anonymized it. As a member of the media, even in my capacity I would not be permitted to participate in their research.