Ten Reasons Why You Should Ignore Exit Polls
1. Exit polls have a much larger intrinsic margin for error than regular polls. This is because of what are known as cluster sampling techniques. Exit polls are not conducted at all precincts, but only at some fraction thereof. Although these precincts are selected at random and are supposed to be reflective of their states as a whole, this introduces another opportunity for error to occur (say, for instance, that a particular precinct has been canvassed ... Full Story »
Posted by Kaizar Campwala
Actually it squares with my personal experience - if exit polls were reliable, at least one major mayoral contest would have had a different outcome. But does it mean media will stop using exit polls? Of course not!