An exit poll is a poll of voters taken immediately after they have exited the polling place.
Unlike an scientific opinion poll, which asks whom the voter plans to vote for or some similar formulation, an exit poll asks whom the voter just actually voted for. This is a method of predicting the result of an election.
Exit polls are also used to collect demographic data about voters and to find out why they voted as they did. Since actual votes are cast anonymously, conducting exit polls is the only way of collecting this information. Exit polls have historically and throughout the world been used as a check against and rough indicator of the degree of election fraud.
Known Problems and Errors
Like all opinion polls, exit polls by nature do include some margin of error. A famous example of exit poll error occurred in the 1992 United Kingdom General Election when two exit polls predicted a hung parliament meaning it would be a 50-50 split between the Labour and Conservative Parties. The actual vote revealed that British Conservative Party under Prime Minister John Major held their position, though with a significantly reduced majority. Investigations into this failure identified a number of causes including differential response rates including a factor known as the Shy Tory Factor (Shy Elephant Factor in the United States), which is known as the use of inadequate demographic data and poor choice of sampling points in attempt to influence voting patterns.