Suppose you want to know the average amount of money spent by the fans attend- ing opening day for the Cleveland Indians baseball season. You get permission from the team's management to conduct a survey at the stadium, but they will not allow you to bother the fans in the club seating or box seats (the most expensive seating). Using a computer, you randomly select 500 seats from the rest of the stadium. During the game, you ask the fans in those seats how much they spent that day.

• Given a reason why this survey might yield a biased result. Explain the likely direction of the bias.