4 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.
How far out the final polls were
The error on the lead between the top two: the final polls' average against the result, in points.
Lab 38.6, Con 21.4: Labour +17.2 (average of 19 final polls, BPC)
Result
Lab 34.7, Con 24.4: Labour +10.3 (Great Britain)
All 19 final polls listed by the British Polling Council overstated Labour's lead, averaging 17.2 points against an actual 10.3, the largest overestimate of Labour since 1979. Pollsters' reviews pointed to too few older and loyal Conservatives in their samples, high refusal rates, over-engaged online panels and some late switching away from Labour.
Con 43.7, Lab 35.8: Conservative +7.9 (average of nine BPC members' final polls)
Result
Con 43.5, Lab 41.0: Conservative +2.5 (Great Britain)
The final polls had the Conservatives 8 points ahead and they won by 2.5, losing their majority; the Conservative share was right and Labour's 5 points too low. Raw poll data were close to the result, and the turnout models pollsters had added after 2015 pushed the headlines towards the Conservatives, while Survation and YouGov's MRP model came close.
Con 33.7, Lab 33.6: a dead heat (average of nine BPC members' final polls)
Result
Con 37.8, Lab 31.2: Conservative +6.6 (Great Britain)
Every BPC member's final poll had the Conservatives and Labour within a point or two of each other, and the Conservatives won Great Britain by 6.6 points and a majority. The Sturgis inquiry found the samples held too many Labour supporters and too many politically engaged people, and ruled out shy Tories and late swing as major causes.
Lab 39.4, Con 38.3: Labour +1.1 (average of the five companies' final polls)
Result
Con 42.8, Lab 35.2: Conservative +7.6 (Great Britain)
The final polls put Labour about a point ahead and the Conservatives won Great Britain by 7.6 points, the worst miss on the lead since polling began. The Market Research Society inquiry blamed late swing, quota samples that did not match the electorate and Conservatives who would not say how they would vote.
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
United Kingdom · 4 July 2024
6.9 pts