All the outreach activity by political campaigns, including door to door canvassing, phone banking, direct mail, and even advertising, has basically no effect on voters’ choice of candidate in general elections, according to a striking new academic study.

The new analysis covers 49 field experiments conducted in real US election campaigns, typically run with cooperation from the campaigns themselves.

Campaigns spend millions of dollars during general elections on canvassing; phone banking; advertising on TV, radio, and the internet; and other efforts designed to win over undecided voters and supporters of the opposing candidate. The new study’s authors, UC Berkeley political scientist Joshua Kalla and Stanford professor David Broockman, conclude that essentially no one targeted is persuaded.

This doesn’t mean that political campaigns never matter. Kalla and Broockman find that these activities can persuade voters in primary elections and during ballot-initiative campaigns. Campaigns can still effectively turn out voters whose minds are already made up about a candidate, and voters can and do change their opinions when prompted by politicians they already support (something a previous study of Broockman’s confirmed).

Moreover, it’s possible that even in general elections candidates can persuade voters by varying their positions on issues (say, defecting from their party consensus to a more popular view) or by receiving different media coverage — factors that Kalla and Broockman’s study doesn’t cover.

But the study should force campaigns to seriously reexamine how they’re spending money, and how they try to persuade winnable voters. Running a successful campaign isn’t impossible. It’s just hard, and might require making some unconventional choices.

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