Measuring Campaign Spending Effects in Post-Citizens United Congressional Elections

Using pooled OLS analysis, early literature found that incumbent and challenger campaign spending exhibited asymmetrical marginal productivities. That is, early scholars found that challenger campaign spending was more productive than incumbent campaign spending. More contemporary literature found this asymmetry was the result of endogeneity bias in the campaign spending covariates. Using 2014 U.S. House election data, we examine the nature of now-ubiqitous independent expenditures and whether these expenditures also exhibit an asymmetry in pooled OLS analysis. In addition to finding that independent expenditures can be differentiated from traditional campaign expenditures in their scope, dispersion, and magnitude, we find that the marginal impact of incumbent and challenger independent expenditures in pooled OLS analysis is symmetrical. We attribute this finding to the limited scope of independent expenditures. Moreover, using our estimated campaign spending effects, we find that political expenditures are rarely pivotal in determining election outcomes.