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Move the polls → Every tool →2 elections where the final polls got the result badly wrong. Each deep dive sets out what the polls said, what happened, what the official inquiries and the pollsters found, what our own data shows, and what the pollsters changed afterwards. Every one of these misses is in the record our forecasts learn from.
The error on the lead between the top two: the final polls' average against the result, in points.
Canada · 14 May 2013
11.5 pts
Every pollster had the NDP ahead, by 7 points on average; Christy Clark's Liberals won 44.1% to 39.7%. The firms' own reviews found they had weighted young, NDP-leaning voters to their share of the population rather than of the people who vote, and missed a late Liberal turnout edge.
Canada · 23 April 2012
16.7 pts
The final polls averaged Wildrose 41, Progressive Conservatives 34; the PCs won 44.0% to 34.3% and kept a 61-seat majority. Pollsters blamed a late swing of undecided and centre-left voters to the PCs after most firms had stopped polling, made worse by a 14-point jump in turnout.
For each country we measure how far the final polls missed at past elections. We take half the average miss off today's polls only where that would have made past forecasts better, testing each election without knowing its result; elsewhere the polls stand as published. Every forecast then runs thousands of simulated elections with polling errors the size of these, so a miss like the ones above is inside our ranges, not a surprise. Polls against results, every election · Our forecast record · Pollster leaderboard