The exit polls are usually considered to be the final before the final results.
The exit polls are usually considered to be the final before the final results. But historically exit polls have gone wrong several times and can go wrong even now. Here’s why? Many a times pollsters have been unable to get the results right, and there has been a bias in the stylized presentations of poll results inclined towards the one party or the other. Flying blind, therefore, are debates about adequate sample size and methodology, randomization strategies and, most importantly, the leap taken from vote share to seats.
The distribution of votes is not even across different polling stations, and also varies at different times of day. As a result, a single exit poll may give an imperfect picture of the national vote. Instead, the exit poll is primarily used to calculate swing and turnout. Pollsters return to the same polling stations at the same times at each election, and by comparing the results with previous exit polls they can calculate how the distribution of votes has changed in that constituency. This swing is then applied to other similar constituencies, allowing an estimate of how national voting patterns have changed.
Like all opinion polls, exit polls by nature do include a margin of error. Sampling and demographic data are very important. A famous example of exit poll error occurred in the 1992 UK General Election, when two exit polls predicted a hung parliament. The actual vote revealed that Conservative Party Government under John Major held their position, though with a significantly reduced majority. Investigations into this failure identified a number of causes including differential response rates (the Shy Tory Factor), the use of inadequate demographic data and poor choice of sampling points.
Because exit polls require a baseline to compare swing against, they are not reliable for one-off votes. Because exit polls can be biased towards certain demographics and miss swings that only occur due to absentee voters.
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This time the Assembly elections have greater element of unpredictability, especially in Uttar Pradesh where Samajwadi Party (SP) and the Congress formed an alliance. A hyper campaign in the state by Prime Minister Narendra Modi himself changed earlier perception that SP-Congress alliance would easily secure a majority. In Punjab, there was a neck-and-neck contest between Aam Aadmi Party (AAP) and Congress. The rebel factor influencing both the Congress and the BJP in Uttarakhand has confounded the political pundits. It is clear that as new alliances form, voting behaviors shift and there is increasing fragmentation of the political system, placing a bigger challenge on forecasting models.