Polls have had a number of high-profile misses in recent elections. We review the current polling environment, the performance of polls in a historical context, the mechanisms of polling error, and the causes of several recent misses in Britain and the US. Contrary to conventional wisdom, polling errors have been constant over time, although the level of error has always been substantially beyond that implied by stated margins of error. Generally, there is little evidence that voters lying about their vote intention (so-called ‘shy’ voters) is a substantial cause of polling error. Instead, polling errors have most commonly resulted from problems with representative samples and weighting, undecided voters breaking in one direction, and to a lesser extent late swings and turnout models. We conclude with a discussion of future directions for polling both in terms of fixing the problems identified and new approaches to understanding public opinion.
Election polling errors across time and space
Are election polling misses becoming more prevalent? Are they more likely in some contexts than others? Here we undertake an over-time and cross-national assessment of prediction errors in pre-election polls. Our analysis draws on more than 30,000 national polls from 351 general elections in 45 countries between 1942 and 2017. We proceed in the following way. First, building on previous studies, we show how errors in national polls evolve in a structured way over the election timeline. Second, we examine errors in polls in the final week of the election campaign to assess performance across election years. Third, we undertake a pooled analysis of polling errors—controlling for a number of institutional and party features—that enables us to test whether poll errors have increased or decreased over time. We find that, contrary to conventional wisdom, the recent performance of polls has not been outside the ordinary. However, the performance of polls does vary across political contexts and in understandable ways.
An Assessment of the Causes of the Errors in the 2015 UK Gseneral Election Opinion Polls
Summary The opinion polls that were undertaken before the 2015 UK general election underestimated the Conservative lead over Labour by an average of 7 percentage points. This collective failure led politicians and commentators to question the validity and utility of political polling and raised concerns regarding a broader public loss of confidence in survey research. We assess the likely causes of the 2015 polling errors. We begin by setting out a formal account of the statistical methodology and assumptions that are required for valid estimation of party vote shares by using quota sampling. We then describe the current approach of polling organizations for estimating sampling variability and suggest a new method based on bootstrap resampling. Next, we use poll microdata to assess the plausibility of different explanations of the polling errors. Our conclusion is that the primary cause of the polling errors in 2015 was unrepresentative sampling.
Why Are American Presidential Election Campaign Polls so Variable When Votes Are so Predictable?
As most political scientists know, the outcome of the U.S. Presidential election can be predicted within a few percentage points (in the popular vote), based on information available months before the election. Thus, the general election campaign for president seems irrelevant to the outcome (except in very close elections), despite all the media coverage of campaign strategy. However, it is also well known that the pre-election opinion polls can vary wildly over the campaign, and this variation is generally attributed to events in the campaign. How can campaign events affect people's opinions on whom they plan to vote for, and yet not affect the outcome of the election? For that matter, why do voters consistently increase their support for a candidate during his nominating convention, even though the conventions are almost entirely predictable events whose effects can be rationally forecast? In this exploratory study, we consider several intuitively appealing, but ultimately wrong, resolutions to this puzzle, and discuss our current understanding of what causes opinion polls to fluctuate and yet reach a predictable outcome. Our evidence is based on graphical presentation and analysis of over 67,000 individual-level responses from forty-nine commercial polls during the 1988 campaign and many other aggregate poll results from the 1952–1992 campaigns. We show that responses to pollsters during the campaign are not generally informed or even, in a sense we describe, "rational." In contrast, voters decide which candidate to eventually support based on their enlightened preferences, as formed by the information they have learned during the campaign, as well as basic political cues such as ideology and party identification. We cannot prove this conclusion, but we do show that it is consistent with the aggregate forecasts and individual-level opinion poll responses. Based on the enlightened preferences hypothesis, we conclude that the news media have an important effect on the outcome of Presidential elections–-not due to misleading advertisements, sound bites, or spin doctors, but rather by conveying candidates' positions on important issues. Winner of the Pi Sigma Alpha Awardfor the best paper at the previous year's meetings of the Midwest Political Science Association. Replication data at the Harvard Dataverse: [https://doi.org/10.7910/DVN/I7GIKD](https://doi.org/10.7910/DVN/I7GIKD).
The Performance of the Polls in the 2019 General Election - British Polling Council
The Performance of the Polls in the 2019 General Election
Opinion | This Is What Will Ruin Public Opinion Polling for Good
Instead of navigating the obstacles to conduct polls with human respondents, pollsters are running A.I. simulations instead. Why?
Do AI and bogus respondents threaten polling’s future?
Courtney Kennedy, vice president of methods and innovation, answers some common questions about the current polling landscape in the U.S.
Why does every poll seem to show a tossup now?
Campaigns see internal polls as tools for fundraising
The Minimal Persuasive Effects of Campaign Contact in General Elections: Evidence from 49 Field Experiments
Significant theories of democratic accountability hinge on how political campaigns affect Americans’ candidate choices. We argue that the best estimate of the effects of campaign contact and advertising on Americans’ candidates choices in general elections is zero. First, a systematic meta-analysis of 40 field experiments estimates an average effect of zero in general elections. Second, we present nine original field experiments that increase the statistical evidence in the literature about the persuasive effects of personal contact tenfold. These experiments’ average effect is also zero. In both existing and our original experiments, persuasive effects only appear to emerge in two rare circumstances. First, when candidates take unusually unpopular positions and campaigns invest unusually heavily in identifying persuadable voters. Second, when campaigns contact voters long before election day and measure effects immediately—although this early persuasion decays. These findings contribute to ongoing debates about how political elites influence citizens’ judgments.
An Examination of Ranked Choice Voting in the United States, 2004-2022
From the perspective of social choice theory, ranked-choice voting (RCV) is known to have many flaws. RCV can fail to elect a Condorcet winner and is susceptible to monotonicity paradoxes and the spoiler effect, for example. We use a database of 182 American ranked-choice elections for political office from the years 2004-2022 to investigate empirically how frequently RCV's deficiencies manifest in practice. Our general finding is that RCV's weaknesses are rarely observed in real-world elections, with the exception that ballot exhaustion frequently causes majoritarian failures.
Simulating Aggregate Electoral Opinion Trajectories with LLM Personas and Media Exposure
LLM-based election simulation has largely been evaluated against a single final outcome, in many cases neglecting how much it can recover the trajectory shaped by media exposure and shifting candidate support. We propose evaluating election simulations in terms of trajectory fidelity: whether persona-conditioned LLM agents can update their beliefs in response to media to reproduce the temporal movement of public opinion, both in aggregate and across demographic subgroups. We design a framework in which each LLM agent carries its belief across time and updates it as new campaign information arrives. We further investigate how performance can vary across simulation design choices such as media exposure model, election context, and survey questionnaire. In a study on the 2026 Seoul mayoral and local elections, we validate simulated trajectories against weekly public-opinion polls and find that simulations that carry prior beliefs across time—rather than simulating each poll date independently—substantially improves alignment with observed polling movement, while the way media exposure is personalized leaves aggregate movement largely intact but reshapes subgroup-level dynamics. We propose a framework for validating simulated opinion trajectories against real-world traces, and discuss the simulation design choices that can influence the performance.
The small effects of political advertising are small regardless of context, message, sender, or receiver: Evidence from 59 real-time randomized experiments
Campaign persuasion operates with notable consistency across political parties, message tone, and information environment., Evidence across social science indicates that average effects of persuasive messages are small. One commonly offered explanation for these small effects is heterogeneity: Persuasion may only work well in specific circumstances. To evaluate heterogeneity, we repeated an experiment weekly in real time using 2016 U.S. presidential election campaign advertisements. We tested 49 political advertisements in 59 unique experiments on 34,000 people. We investigate heterogeneous effects by sender (candidates or groups), receiver (subject partisanship), content (attack or promotional), and context (battleground versus non-battleground, primary versus general election, and early versus late). We find small average effects on candidate favorability and vote. These small effects, however, do not mask substantial heterogeneity even where theory from political science suggests that we should find it. During the primary and general election, in battleground states, for Democrats, Republicans, and Independents, effects are similarly small. Heterogeneity with large offsetting effects is not the source of small average effects.
Mainstreaming the populist radical right? Online news exposure and voting behavior in the 2019 European Parliament election
How does media exposure relate to support for radical right populist parties (RRPPs)? We contribute to this classic debate by analyzing the web browsing histories and survey responses of six thousand study participants in France, Germany, Italy, Spain, and the UK during the 2019 European Parliament election. Linking direct measures of online news exposure to voting behavior allows us to assess the effects of the salience of issues politicized by RRPPs on their electoral support. The likelihood to vote for RRPPs was higher when the EU was more salient in individual media diets, while exposure to the less salient issue of immigration did not increase the propensity to vote for RRPPs. Alongside consistent results for other party families and interactions with pre-existing voting intentions, the findings indicate that the electoral effects of online media are contingent on the overall salience of a specific issue and voters’ predispositions.
Anticipating Election Misinformation in the 2026 Midterms
Election misinformation often follows the same pattern every cycle. Here are some of the false and misleading claims that voters are likely to see.
Guardian Essential poll: Labor’s housing and tax changes fail to win over voters as support for One Nation swells
Just 25% of Australians polled back the budget while the majority believe the government has fallen short of expectations over the past year
Everyone’s talking about the polls: The Age does it differently
Where voters will ultimately land on the question of Victoria’s leadership is becoming increasingly difficult to predict. Fortunately, Age readers are in good hands when it comes to assessing the political mood.
