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Brexit exit polls? Don’t hold your breath.

Britain's vote on whether to leave the European Union will be watched closely by people all around the world. Yet the world will have to wait to get a sense of what will actually happen next — polls close at 10 p.m. local time, and the first results aren't expected until hours later. When the final result comes in, it will probably be the early hours of Friday morning.

There will be no clear indications any earlier about which side has won because there will be no public exit polls. Why not?

Britain has tough laws on what information you can publish on election day. For example, the BBC is compelled to stick to reporting on only inarguably factual events — which politicians went to the polling station, for example. And despite being common practice in most parts of the world, publishing exit poll data — data from voters surveyed as they exit the polling stations — before 10 p.m. GMT (5 p.m. Eastern time), when the polls close, is illegal.

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Our reporters on the ground in London are recording the historic day in the United Kingdom. (Video: Karla Adam, Griff Witte/The Washington Post)

This is spelled out in British law. Under Section 66A of the Representation of the People Act of 1983, it is unlawful to publish "any statement relating to the way in which voters have voted at the election where that statement is (or might reasonably be taken to be) based on information given by voters after they have voted." In theory, anyone who publishes an exit poll before 10 p.m. local time in Britain could face a £5,000 ($7,400) fine or even six months in jail.

This doesn't mean that you can't conduct exit polls during the day and then publish them after 10 p.m., of course. In most regular elections, major media outlets such as the BBC, ITV and Sky commission their own polls and then publish them immediately after the end of voting. This election, however, they have not. As the Independent's John Rentoul explains, this is because of limitations of the data. The last nationwide referendum in Britain was held in 1975, when the country voted on membership in the E.U.'s predecessor, the European Economic Community. No exit poll was conducted then, meaning there is no baseline against which to measure information from today.

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Last month, the Financial Times reported that some hedge funds and investment banks have commissioned private exit polls. These polls will not be released publicly, so they are not subject to the same laws. Instead, they will be used to inform financial decisions before the final results of the vote come out. As such, anyone wanting an early indication of how the vote is heading may want to pay attention to foreign exchange markets for clues.

Is the world really missing out by not having exit polls to understand the Brexit vote? Yes and no. Exit polls are generally considered among the most accurate ways of polling during elections. On polls conducted ahead of elections, you are asking people how they intend to vote. Until the very last moment, those people could change their minds. On the other hand, when you conduct an exit poll, you are asking people how they have voted.

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This doesn't mean that exit polls are perfect. In fact, recent experience suggests exit polls can be very wrong. Last year, a number of Israeli exit polls completely missed what would go on to be a clear win for Prime Minister Benjamin Netanyahu. In the 2004 U.S. presidential election, a number of polling companies were found to have made errors that led to inflated estimates of support for Democrat John Kerry in exit polls. There have been problems in Britain, too. In 1992, exit polls suggested that the country would be heading toward a hung Parliament (instead, the Conservatives won quite comfortably).

However, most recent exit polls in Britain have been fairly accurate — sometimes even completely contradicting pre-election polls. During last year's general election, one politician was so shocked by the exit polls that he pledged to eat his own hat if they were correct. Sadly, he did not keep his end of the bargain.

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