What you need to know about exit polls

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, they compare results to pre-election polls and the voting history in that precinct, and have statisticians and political experts carefully review the data.

After polling places close, 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 2014 election, just over a third of Americans voted before Election Day, using some form of absentee or early voting.

Brendan Smialowski/AFP/Getty ImagesPeople wait to cast their ballots during early voting at a community center, Oct. 25, 2018, in Potomac, Md., two weeks ahead of the key US midterm polls.

That percentage is on track to be even higher in 2018. Capturing information about these voters is challenging, but it is critical to report accurate information about all voters.

In states with a high number of people who vote absentee or early, telephone polls are conducted to reach those voters. In some states with a lot of early in-person voters, exit polls are conducted with these voters as they leave the polling place. Data from polls of absentee and early voters are combined with the Election Day 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 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.

Sourse: abcnews.go.com