First things first: There's only one official exit poll.
Though networks take ownership of the information — "according our CNN exit poll" yada yada — in reality they're all using the same data, supplied by Edison. In a pool-purchase arrangement, Edison feeds data to AP, CBS, NBC, ABC, CNN and FOX.
Edison's exit pollsters manage some 1,000 stations nationwide, where temporary employees survey nearly 100,000 voters, using written questionnaires submitted anonymously. Pollsters relay results to the firm, which submits them to the networks.
While Edison compiles data all day, it delivers no data to the networks before 5 p.m. on election night, meaning "early" exit poll results should be viewed with suspicion.
"If you see exit polling information during the day it's most probably bogus," Rosin said. "Anything before 5 p.m. I can assure you it's bogus."
Even after receiving the first wave of data from Edison, "no network will officially put out information until all polls are closed in a given state," Rosin said.
But after 5 p.m. and before the close of voting, some networks may leak info. This muddles the waters because the true leaked info is out there with bogus "leaked" info. "Just because it's after 5 p.m. doesn't mean it's not bogus," Rosin said.
And even confirmed polling numbers must be taken for what they are: estimates. Rosin warns that exit polls are not infallible indicators. "In a close election the exit polls are not definitive. The margin of error is different in each state," he said.
Often forgotten is the value of polls beyond prediction. "The amazing thing about the exit polls," Rosin said, "is the real value comes in the analysis — why did they win? We ask a lot of questions about who are you, what are your values, what drove your vote? People only seem to think about the projections, but truly the analysis is where the value is. Someone is going to win, but it's important to know why they won. ... The analysis, for weeks afterward, will be what drives the discussion."