A graduate student conducts a research project about how adult Americans send thank-you notes. She uses the U.S. Postal Service to mail a survey to 500 adults that she knows and asks them to mail back a response to this question: "Do you prefer to send thank you notes by e-mail or snail mail (the U.S. Postal Service)?" She gets back 65 responses, with 42 of them indicating a preference for snail mail.
Identify the sample, population and sampling method. Then comment on whether you think it is likely that the sample is representative of the population.