An independent inquiry is to look at the accuracy of UK election polls, after they failed to predict the Conservatives' lead over Labour.
The British Polling Council (BPC) will examine "apparent bias" and make recommendations for future polling.
It follows widespread shock on Thursday at a BBC exit poll, which showed the Tories comfortably ahead of their opponents.
The party went on to win an absolute majority, with 331 seats.
Labour took 232 seats, the SNP have 56, the Liberal Democrats finished on eight, Plaid Cymru won three and UKIP and the Greens took one seat each.
In the run up to the election, almost every major national poll had predicted the race was neck and neck between the two main parties.
The BPC said in a statement: "The fact that all the pollsters underestimated the Conservative lead over Labour suggests that the methods that were used should be subject to careful, independent investigation."
It announced Professor Patrick Sturgis, director of the Economic and Social Research Council's National Centre for Research Methods, would chair the inquiry.
Chancellor George Osborne said the pollsters would face "a big post-mortem".
Meanwhile, market research agency Survation said it had "chickened out" of publishing a telephone poll on Wednesday evening, which showed the Tories on 37% and Labour on 31%.
Its chief executive Damian Lyons said he would "always regret" the decision, but the results seemed "so out of line" with previous polls.
2015 election results map
David Cowling on how the pollsters got it so wrong
Newsnight reporters and producers' rolling election analysis