Online polls
The online polls conducted in the lead up to the referendum predicted correctly that Britain would Brexit from the EU. The online polls highlighted that the race between the Remain and Leave camps was very close; however, Leave had the slight advantage.
Turnout needs to be treated separately (6/7) https://t.co/Xo8qpxbDVO pic.twitter.com/JPt4ivRSK4
— YouGov (@YouGov) June 28, 2016
Three days before the vote, a poll by YouGov showed that the Leave camp had a two point lead. However polls have not always been correct.
Shortly before the last General Election, it was predicted that the Labour Party would be the winners or there would be another coalition. That didn't happen and the Conservative party won with a big majority.
Betting Markets Know Nothing
It wasn't just opinion polls trying to predict the outcome of the referendum.
The betting markets also attempted to look in and news websites included live tracking of betting odds.
Throughout the campaign the betting markets showed huge confidence in a Remain victory and odds on Brexit were often as long as 5:1, including on the day of the vote when at one point they hit 16:1.
Online Polling More Accurate
Telephone polls showed that Remain were comfortably ahead, sometimes by as much as 18 points. However, the online polls showed that the Leave side was in front. It can therefore be argued that the results from telephone polls are subject to more problems and can be skewed.
Bad telephone polling may have lost remain the campaign (5/7) https://t.co/Xo8qpxbDVO
— YouGov (@YouGov) 28 June 2016
The Remain camp hired a former City trader to assess whether online polls were more reliable than phone polls. The results came back that online polling was wrong and there analysis was even featured on Newsnight.
As first revealed on #newsnight, online polls seem to be overestimating support for #Brexit https://t.co/zgTmJPLs7Z pic.twitter.com/Wahc54HTFc
— Matt Singh (@MattSingh_) 10 May 2016
Polling Works
Analysts have argued that the Remain team may have been misled by this information and led to feel safe that Britain would vote to stay in the EU. If they had known perhaps that their position was not as secure, maybe they would have changed their campaign?