EXPLAINER: How Exit Polls Work

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With the presidential candidates tied in so many polls as they head into Election Day, it could take a while to project a winner in this very close race.

Results in other statewide races may be reported as soon as the polls close on Nov. 6, and some early numbers, such as who turned out to vote and why they voted the way they did, will be available to report.

ABC News will draw on many sources to tell the Election Day story, but some of the most important information will come from exit polls. There will be a national exit poll along with statewide exit polls in 31 states.

Here are some of the frequently asked questions about exit polls, along with information about how to find out what exit polls are reporting.

What are exit polls?

Exit polls are surveys conducted as voters leave their polling places on Election Day. Reaching voters at that moment is important, because it overcomes the problems of conducting election polls by telephone: People sometimes misreport whether they voted. The who-won-and-why-did-they-win reporting on election night is gleaned mainly from exit poll results.

Who conducts exit polls?

ABC News and polling partners CBS, CNN, Fox, NBC and The Associated Press comprise the National Election Pool. The pool has contracted with Edison Research to run the 2012 exit polls.

How are exit polls conducted?

Interviewers stand outside polling places in randomly selected precincts. They attempt to interview voters as they leave polling places at specific intervals (every fourth or 10th voter, for example).

Voters who agree to participate in the poll fill out a paper questionnaire and place it in a ballot box. Interviewers phone in results three times during the day.

When a voter refuses to participate, the interviewer notes the sex and approximate age and race of that voter. In this way, the exit poll can be statistically corrected to make sure all voters are fairly represented in the final results.

What sorts of questions are asked in an exit poll?

The typical exit poll questions ask voters whom they just voted for in key races; what opinions they hold about the candidates and key issues; their demographic characteristics.

Here's an example of an exit poll question from this year:

Which ONE of these four issues is the most important issue facing the country?

Health care

The economy

Federal budget deficit

Foreign policy

Are exit polls accurate?

Exit polls, like other surveys, are subject to sampling errors. Therefore, before news organizations report any exit poll results or make projections, they compare results to pre-election polls and past-precinct voting history. Statisticians and political experts carefully review the data. As the actual vote count comes in, the exit poll results are updated to reflect that information.

How do exit polls account for the people who vote early or by mail?

In the 2008 election, nearly one-third of Americans voted before Election Day, either by absentee ballot or some form of early voting. According to estimates by political scientists, the early vote count could be as high as 40 percent in 2012. Capturing information about these voters is challenging, but it is critical to report accurate information about all voters before projecting races.

In states with high numbers of absentee/early voters, pre-election telephone polls are conducted. The NEP will conduct more of these polls in 2012 than in any recent election. Data from these telephone surveys will be combined with the exit poll data to provide a more complete portrait of voters.

When will exit poll results be reported?

On Election Day, there is a strict quarantine on any news coming from the early waves of exit poll data until 5 p.m. ET. By about 5:45 p.m., some initial demographic information about voter turnout will be reported on ABCNews.com.

No winners will be projected, however, until polls are closed, so announcements come state-by-state as individual state polls close. Information will be updated constantly throughout the evening on ABCNews.com and on all ABC News programs.