Research
How the forecast works, in full
The 10 papers behind our France forecast (27,384 words): how far the polls have missed, how we correct them, the seat model and the tests.
These papers set out every part of our method: what we measure, how we correct the polls, how votes become seats, how uncertain the result is, and what we have tested and rejected. Figures marked Live are computed from the database each time the page is built, so they always match the forecast. En français
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10 papers · about 27k words · Our method, in short · How the elections work · Data sources
France
- Forecasting French elections from imperfect polls: an overview The France section forecasts the 2027 presidential election and a possible National Assembly election with the rule used for Great Britain: take half the average past miss off today's polls, but only where that would have improved past forecasts made without knowing the result. Round-one presidential polls fail that test and are taken as published; round-two polls, which have overstated the RN candidate at every runoff the RN has reached, and legislative polls pass it and are corrected. This paper sets out the evidence, the seat model, the sources of uncertainty and what the forecast does not claim, and maps the other France papers.
- Measuring French polling error, 1965–2024 We compare every pollster's final poll with the result at the presidential elections of 2002–2022 (by candidate family), the legislative elections of 2017–2024 (by bloc) and, more thinly, every presidential election since 1965. Round-one misses average about a point per family but change direction; round-two polls overstated the RN candidate at all three runoffs the RN reached; legislative polls overstated the RN and its allies three times out of three. Pollsters' seat projections between the legislative rounds missed by far more than the vote shares.
- How we read French polls: what we correct, what we don't, and why French presidential round-one polls have no stable lean and are taken as they are; round-two polls have overstated the RN candidate at every runoff the RN has reached, and legislative polls have overstated the RN at each of the last three Assembly elections, so both are corrected. Assembly seats come from a circonscription model of qualification, withdrawal and duels fitted on 2024.
- The 2027 presidential forecast: line-ups, runoffs and simulation We follow two line-ups tested by French pollsters, average each pollster's latest poll, take round one as published and correct round-two head-to-heads for the RN's record of being overstated. Chances of qualifying and of winning come from 20,000 simulated elections in which each candidate's round-one error has the size of their family's past misses and the runoff is drawn from the corrected head-to-head with a spread of about 4.4 points. The paper sets out each step formally, with a worked example and the choices we tested and did not adopt.
- From votes to seats in the National Assembly Each of the 577 circonscriptions starts from its 2024 round one, moves by uniform swing, and goes through the legal thresholds for round two, a withdrawal rule and a model of two-candidate duels fitted on the 403 duels of 2024. The duel model picks 370 of those 403 winners in sample but, fitted on one election and tested on the other, does little better than naming the round-one leader, and pollsters' own seat projections have missed by even more. The paper describes each step, its tests, the poor fit for overseas and abroad seats, and why the 80% ranges are too narrow.
- From today to polling day: drift in French presidential polls Polls taken months before a French presidential election have missed the result by far more than final polls. Unlike in Britain, pulling parties back towards their previous result did not help when tested on 2002–2022, because French party families rise and fall too much between elections, so the polling-day forecast takes today's polls as they stand and adds the uncertainty that the time remaining has carried in the past, fitted as a curve that grows with the logarithm of the days left.
- If we're wrong: replaying past polling misses on today's French polls For a National Assembly election, the site replays the round-one polling misses of 2017, 2022 and 2024 on today's legislative polls and works out all 577 seats again under each, counting a seat as at risk when at least one past miss would change its winner. For the presidency it replays the round-one misses of 2002 to 2022 on today's candidates. The lenses are scenarios shown beside the projection, not averaged into it, and they hold round-two behaviour fixed, which is where the largest French seat misses have come from.
- Rating French pollsters: accuracy, the lead and openness We score each French pollster out of 100 on its final round-one polls at the presidential elections of 2002 to 2022 and the legislative elections of 2017 to 2024 (70 points, shrunk towards a poor pollster), and on six openness items specific to France, starting with raw figures in the notice filed with the Commission des sondages (30 points). Because French final polls have missed by less per party than British ones, the same scale gives most French pollsters an A or B, and we explain why we keep it. The paper also covers each pollster's lean against today's average and the raw figures printed by OpinionWay and Cluster17, which pull in opposite directions and are shown but not used.
- The French data: results, maps, statistics, deputies and polls Official results, circonscription boundaries, INSEE statistics and the list of deputies come from French open data, almost all under the Licence Ouverte; polls come from pollsters' releases and Commission des sondages notices, with Wikipedia as a marked last resort. Every poll carries a source grade (A primary, B press report, C secondary): of the 172 French polls held in September 2026, 40 were grade A. The paper sets out each source, how results are grouped into candidate families and blocs, the checks, the daily check for new notices and the admin entry and CSV import, what we deliberately leave out, and the licences.
- What we don't know yet: limitations of the French forecast The French forecast rests on five presidential and three legislative elections and 99 final polls, enough to see a pattern in round-two polls but not to be sure it will hold. The line-ups are unsettled, the last legislative polls date from autumn 2025, the seat model moves every circonscription uniformly from 2024, and round two depends on withdrawals and transfers that changed sharply between 2022 and 2024. This paper sets out each weakness, including the 38 seats overseas and abroad, the scarcity of raw figures and the ban on publishing polls before the vote, and what evidence would change the method.