A local TV station conducts an "Instant Poll" to predict the winner in the upcoming mayoral election. Evening news viewers were invited to phone in their votes, with the results to be announced on the late-night news. Based on the phone calls, the station predicted that Joseph Serra would win the election with 52% of the vote. They were wrong: Serra lost, getting only 46% of the vote. This faulty prediction may be the consequence of what kind of bias?