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.
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.
The final polls had the PP 5.7 points ahead of the PSOE and the PP and Vox close to a majority; the PP won by 1.4 points and the right finished six seats short. Every private pollster understated the PSOE, and only the CIS, which named the wrong winner, did not.
All 22 final polls had Unidos Podemos second, ahead of the PSOE, and the PP on under 30%; the coalition finished third with 21.2% and the PP won 33.0%. The polls counted the December voters of Podemos and Izquierda Unida as if they would all back the joint list, and more than a million did not.
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
Spain · 23 July 2023
4.3 pts