Are Political Campaigns Changing Voters’ Opinions?
In 2020, the US will spend at least $ 6 billion on political campaigns – over $ 2 billion on the presidential election alone. These astronomical numbers fuel fears that public opinion is being manipulated, either through traditional techniques such as TV advertising, cold calling, and mailings, or through more sophisticated technologies that use big data for targeted advertising.
But are these fears justified? Political scientists have been systematically testing the effectiveness of political campaigns for almost two decades. To find out if a campaign strategy is working, randomized control studies are the best solution. For example, you can randomly select specific neighborhoods to receive a campaign mailing supporting a specific candidate. If these areas vote in greater numbers for the candidate, it should be because the mailing influenced their choice.
This is what Alan Gerber of Yale University, a pioneer in the field, did in one of the first studies of its kind, published in the journal American Behavioral Sciences in 2004. Almost 100,000 households received mailings in favor of a congress candidate. Were these people more likely to vote for the candidate? Not a little. (To be more precise, they did this by 0.2%, which is not statistically significant.) The study was convincing because it was large: As a rule, the larger the sample, the more solid the conclusion.
In some other studies that Prof. Gerber conducted, he found that campaign mailings had an impact on the votes. But these experiments had smaller samples, and their results were conflicting – in one of them, mailings seemed to reduce the likelihood that people would vote for the candidate. The best way to understand such studies is to summarize them in a meta-analysis, a statistical test that aggregates the results of many experiments to see if robust patterns emerge.
Last year, in an article published in the American Political Science Review, political scientists Joshua Kalla from Yale and David Broockman from Stanford looked at all of the studies that had used randomized trials to test the effectiveness of political campaigns and added nine of their own studies to final measure . The entire spectrum of campaign tools was covered – mainly acquisition, telephone calls and mailings, some studies with a focus on TV and online advertising. The conclusion of the researchers was clear: “The best estimate of the impact of campaign contacts and advertising on American candidate selection in general elections is zero.”