Suppose that a television network wants to know how daytime television viewers feel about a new soap opera the network is broadcasting. A staff member suggests that just after the show ends they give two phone numbers, one for viewers to call if they like the show and the other to call if they don’t. Give two reasons why this method would not produce the desired information. (The network is interested in all daytime television viewers. Who is likely to be watching just after the show, and who is likely to call in?)