The Truth About Exit Polls
There’s much consternation in some political quarters today about the apparently inaccuarte early exit polling out of Wisconsin last night which caused all three cable news networks to initially report, after Wisconsin’s polls had closed at 8:00pm Central Time, that the race between Scott Walker and Tom Barrett was “50-50” only to drastically change their tune less than an hour earlier.
So, what went wrong?
Well, for the most part, it involved using exit polls for something other than the purpose for which they were intended:
[T]he fault is less about the exit polls themselves, than it is about a widespread, albeit understandable misrepresentation of the numbers.
The exit poll is, after all, a poll, complete with a margin of sampling error and other foibles.
One issue with the exit polling for the recall election was that there was no telephone survey of absentee voters. NBC News estimates at least 15 percent of all voters voted that way, and that they favored Walker over Barrett. The first exit poll numbers to include estimates of the vote breakdowns for absentee voters was the release a half-hour after poll-close, perhaps accounting for the shift from 50-50 to 52-48.
Another, easily forgotten aspect of early numbers is that they are preliminary. The exit poll includes several rounds of interviews with randomly selected voters as they leave polling places (sometimes augmented with telephone polls of early and absentee voters). Different types of people vote at different times of day, with results from morning interviews varying from those at other times.
As it happens, the first round of interviews had Walker way up, the second round had Barrett at 50 percent and Walker at 49 and the third had Walker up again.
When actual precinct level results start to come in, exit polls are adjusted accordingly.
One way to avoid Election Day confusion is to focus on what exit polls are good for — the tally of how different groups voted in an election, and their relative size in the overall electorate — not what they’re not: predicting results.
While conservatives are using what happened last night as evidence of some political bias and/or conspiracy, in reality it’s quite apparent that what’s happening is that the “news” networks use these exit poll results irresponsibly because it helps them to sensationalize what is otherwise the rather tedious process of waiting for results to come in. In some cases, such as when the media calls a state like New York or Kentucky on a Presidential Election night right after the polls close, it’s not really a big deal because it’s rather obvious what’s going to happen. In others, such as what happened last night, opening up your 9pm Election Night coverage by saying that the race is “neck and neck” because that’s what the preliminary exit poll data says is just irresponsible journalism. The networks who did it, all three of them, ought to be ashamed of themselves.
As noted above, exit polls are great for helping to understand how different groups voted, or what issues were most important to voters on Election Day, but they’re positively useless in predicting the outcome of an election. The best advice would be to ignore them, but I think we both know the media won’t do that.