Vote 2016: How Exit Polls Work

— -- 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 problem pollsters have conducting election polls by telephone: people on the phone sometimes misreport whether they voted. The "who won and why did they win" reporting on election night is gleaned mainly from exit poll results, though absentee and early voting participation increases with every election cycle.

How are exit polls conducted?

Interviewers stand outside polling places in precincts that are randomly selected. They attempt to interview voters leaving the polling place at specific intervals (every third or fifth voter, for example). Voters who agree to participate in the poll fill out a short 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 gender 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 questionnaire asks questions of voters that measure the following: who they just voted for in key races; what opinions they hold about the candidates and important issues; the demographic characteristics of the voter.

Here's an example of a 2016 exit poll issue question:

Do you think the condition of the nation's economy is:

Are exit polls accurate?

Exit polls, like any other survey, are subject to sampling errors. Before news organizations report any exit poll results or make projections, therefore, they compare results to pre-election polls, past precinct voting history, and have statisticians and political experts carefully review the data. After the polls close the exit poll results are weighted using the actual vote count to make the data more accurate. Even projections that are made without any actual vote data are not based solely on the results of exit polls.

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

In the 2012 election, just over one third of Americans voted before Election Day, using some form of absentee or early voting. That percentage is on track to be even higher in 2016. Capturing information about these voters is challenging, but it is critical to report accurate information about all voters. In states with high numbers of absentee/early voters, telephone polls are conducted to reach those voters. Data from these telephone polls are combined with the exit poll data to provide a complete portrait of all 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 5:00 p.m. ET. By about 5:45 p.m., some initial demographic information about voter turnout will be available on ABCNews.com.

Winners will not be projected until polls are closed, so announcements come on a state-by-state basis as individual state polls close. Information will be constantly updated throughout the evening on ABCNews.com and on all ABC News programs.