Ignore exit polls

Unparalleled election prognosticator Charlie Cook, back in 2006:

Having worked at networks for every election since 1992, my advice on exit polls?  Ignore them.  They aren't very good.  Any contest that is so close than you couldnt figure out who was going to win by reading the previous week's Time or Newsweek is too close for an exit poll to tell you anything.  It's a poll, it's not a count.

In 2004, while you guys all got your panties in a wad over the exit polls, I stayed away from the network where I worked until 5:00pm, did not allow anyone to tell me over my cell phone or open any emails on my blackberry that appeared to have anything about exit polls and any emails that looked like they had any exit poll data in it, I immediately closed the email before seeing the results.  

As a result, I entered the vote count with a clear mind, no preconceived (erroneous) thoughts about what was going on and did a better job.  If you guys had seen as many screwball exit polls as I have, you would too.

The best use of exit polls is to be able to look and say, approximately, how various demographic groups voted, after the election is over and after the data have been cleaned up.  Anything more and you are simply engaging in mental masturbation.

I see them as rough estimates of how various demographics are voting. They might even be a little fun, a great way to pass time the last couple of hours before the polls close.

But they are not predictive, they are not decisive, and eventually they get cleaned up with real data after all the votes have been counted.

Update: Mark Blumenthal:

Just to put a bit more emphasis on the previous update: The results "leaked" for Ohio at this hour on 3/4 showed Obama leading by 2. Clinton won by 10.

And:

I see that at least one publication has posted leaked exit poll results that most will consider a bit surprising. Please keep in mind that these leaked estimates have typically shown a skew in Obama's favor. See the table in my 3/7 National Journal column. Errors on the margin occurred (at this hour) in Obama's favor in 18 or 20 states I looked at, averaging 7 points in Obama's favor.