Understanding Exit Polls: An Explainer

Most election watchers know that exit polls provide important data that is in some way incorporated into how races are called. But what exactly is an exit poll, who conducts it, and how does it combine with the vote count in a particular race to determine the winner? ABC News' Robin Sproul helpfully explains:

ABC News and polling partners CBS, CNN, Fox, NBC and The Associated Press jointly comprise the National Election Pool. The pool has contracted with Edison Research to run exit polls in 26 states this Election Day. The 26 state exit polls cover top statewide races, but not local or district level races. ...

Exit polls are surveys conducted as voters leave their polling places on Election Day. ... The "who won and why did they win" reporting on election night is gleaned mainly from exit poll results. ...

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. ...

Read the full story at ABC News.