Does negative political advertising actually work?

The study "A Border Strategy Analysis of Ad Source and Message Tone in Senatorial Campaigns," which will be published in the June edition of INFORMS journal Marketing Science, is co-authored by Yanwen Wang of the University of British Columbia in Vancouver; Michael Lewis of Emory University in Atlanta; and David A. Schweidel of Georgetown University in Washington, D.C.

The study examined political advertising and its impact on the share of the vote in two-party races in 2010 and 2012 U.S. senatorial campaigns. It focused on advertising across the borders of designated marketing areas (DMAs), where discontinuities may exist that lead to different levels of exposure to political advertising. DMAs are typically used by marketers to define marketing areas by town, city or major metropolitan area.

The study authors found that negative advertising is powerful in terms of influencing preferences and voter turnout, but not across the board. When the ads are from the candidates or campaigns themselves, the negative advertising was found to be more effective. When the negative advertising was from Political Action Committees (PACs), it was not as effective.

"We studied advertising discontinuities along DMA borders within states to study the impact of political advertising based on the source of the advertising and message tone," said Yanwen Wang. "Our analysis used a data set from the 2010 and 2012 senatorial elections, and it included all the within-state DMA borders for 2010 and 2012 senatorial elections, gross rating points for every ad (GRP) in these DMAs, every ad sponsorship and tone, demographic information, and county-level votes."

Using GRPs to measure effectiveness, the study found that negative political advertising has a significant effect on two-party vote shares. On the other hand, positive political advertising was found to be ineffective.

When the researchers compared campaign ads created by candidates' campaigns to those created by PACs, they found that advertising sponsored by PACs is significantly less effective in terms of two-party vote shares and ineffective in terms of turnouts. "We find that negative advertising GRPs from candidates are approximately twice as effective as advertising GRPs sponsored by PACs," said Michael Lewis. "In terms of mobilizing voters, we find that negative advertising GRPs from candidates have a significant effect on voter turnout, but negative advertising from PACs is ineffective in mobilizing turnouts."

According to study author David Schweidel, the credibility of the person or group behind the ad may be the determining factor on the effectiveness of the advertising.

"We believe that the pattern of results in our study is due to differences in source credibility across the various ad sponsors and that advertising by PACs may lack credibility."