Study finds political campaigns can change voters’ choices – but not their political views

A new paper in The Quarterly Journal of Economics, published by Oxford University Press, measures the overall impact of election campaigns and finds that televised debates have little effect on shaping voter choice. Information obtained from other sources, such as the media, political activists and other citizens, is more important.

Researchers and experts have long debated the impact of political campaigns. One view is that the weeks leading up to the election are a critical period. Campaign information can help voters evaluate the performance of incumbents, compare the qualities and positions of all candidates, and perhaps even reconsider their policy preferences. However, some researchers argue that campaigns have little effect because most people make up their minds about their candidate long before the election.

The researchers here used survey data from 62 elections in ten countries (Austria, Canada, Germany, Italy, the Netherlands, New Zealand, Sweden, Switzerland, the United Kingdom, and the United States) since 1952 to study how voters make their choice. The data included 253,000 observations. The authors looked at the difference between who voters said they would vote for, before the election, and who they said they voted for, after the election.

The survey revealed that the proportion of people with the same voting declarations before and after the election increased by 17 percentage points in the 60 days before the election, from a baseline of 71%. On the last day before the election, 12% of voters still do not know (or will not say) who they will vote for or indicate a different voting intention than their final choice. Overall, 17% to 29% of voters make up their minds during the last two months of election campaigns. This large increase in the consistency of individual vote choice is associated with a 5 percentage point reduction in the distance between predicted and final vote shares: voters deciding in this period significantly influence election outcomes.

In a given election, younger and less educated voters are more influenced by campaign information, and voters who identify strongly with one party are less influenced. Changes in vote choice are driven by changes in voters’ beliefs about candidates’ positions and attributes, as well as by changes in the issues voters consider most important. Instead, their policy preferences remain stable throughout the campaign.

The researchers here also investigated evidence about the relative importance of different sources of information. Information from televised debates had little effect on voters’ decisions. Shocks such as natural and technological disasters, occurring independently of the campaigns, did not appear to change voters’ decisions either. These results suggest that information received throughout the campaign from sources such as news or friends is more important.

The authors were surprised to find that televised debates—despite the interest they generate, the large audiences they attract, and the extensive media commentary they generate—do not seem to change voting behavior. Overall, the results suggest that even if voters sometimes appear relatively uninformed and indifferent, their voting choices actually depend on extensive information beyond the debates.

“Since our data cover 62 elections, it enables us to compare the importance of election campaigns in different settings,” said the paper’s lead author, Vincent Pons. “Campaigns play a key role in all periods and in all the countries we study. But interestingly, the percentage of voters who changed their minds in the last two months before an election is much smaller in the US than in Canada, the Germany, New Zealand and all the other democracies in our sample.’