Around the world, election exit polls are used as a standard of election verification. In the US, media exit poll operators note that their polls are not designed to detect fraud. Rather, their purpose is to project winners of races and provide material for news coverage. (q.v., National Election Pool)
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Description
An election verification exit poll’s objective is not to predict election results, but rather to audit or verify the accuracy of vote counts in selected precincts. Therefore, EVEP pollsters focus on targeted percentsts, polling very comprehensively so official election results in these targeted precincts can be verified. For example, in the 2006 United States Congressional elections, The Warren Poll (sponsored by Election Integrity) interviewed close to 6000 voters in selected precincts in Montgomery, Delaware, and Chester counties in Pennsylvania.
Due to the comprehensive nature of exit polls, if EVEP results differ significantly from the actual reported results in the targeted precincts, it is reasonable to conclude that something is wrong with the official count, especially considering that exit poll methodologies have normally proved quite reliable. Notwithstanding, an EVEP is still a survey and may suffer from the many problems that any survey may experience (e.g. weather, interviewer interaction, distance restrictions, etc.).
Use
Exit polling in the United States, as well as in other countries of the world, have been used to question the official results. For example, in the 2000 election in Yugoslavia, Slobodan Milošević claimed that he had defeated Vojislav Koštunica. However, exit polling cast great doubt as to the accuracy of the reported count, suggesting that the vote count had been corrupted. Public and media pressure eventually forced him to concede.
The introduction of new electronic voting machines, especially ones that produce no paper trails, has caused many groups, including a considerable number of state and national political leaders, to call for remedies to vote count problems. Some have specifically advocated the use of EVEPs, especially in precincts that have historically had problems with fair vote counts. EVEP proponents believe that EVEP findings can be used to challenge dubious official vote counts in court.
However, EVEPs have inherent weaknesses, especially as legal weapons in lawsuits.EVEP results are not 100% accurate; they are subject to an error margin, making them very difficult to use to challenge any election results that are close. Also, obtaining a truly random representative sample is problematic since some voters will not respond to the poll. Another serious problem is caused by the various ways people can vote (e.g., early voting, absentee voting, provisional voting, and regular voting). EVEP pollsters cannot poll those who vote early or vote absentee. If election board officials merge all the different kinds of voting alternatives, pollsters cannot accurately verify vote counts because EVEP pollsters interview only those who have cast regular ballots, or possibly provisional ballots.
Contrast with media exit polls
While media polls could be used to detect, and even prosecute, fraud if the data is made available, the purposes are different and so are methodologies used. The purpose of a media exit poll is to strategically poll many precincts to obtain a representative sample for an entire district (e.g., state, city) so election outcomes can be predicted. Most of the polling is done well before polling places close on Election Day so the exit poll results can be tabulated and presented by the news outlets immediately after the polls close. Since verifying particular precinct results is not an objective of media exit polls, typically only 1000-2000 voters are interviewed in an entire state, meaning that relatively few voters are interviewed in any given precinct. Consequently, an EVEP should be considerably more reliable (given that there is no within precinct bias) for the targeted precincts than media exit polling would be since a much larger sample of voters would be interviewed in these selected precincts. Media exit polling has incidentally served to cast doubt on official vote counts, but such polling is not particularly designed to verify election results.