Table 1 Meta-analysis of average treatment effects of advertisements on target candidate favorability and vote choice.

Observations are CATE estimates for each advertisement, conditional on subject partisanship and battleground residency. The signs of the outcomes are scaled with respect to the valence of the advertisement: Higher values indicate that promotional advertisements had positive effects on target candidate favorability or vote choice and that attack advertisements had negative effects. All meta-regressors have been demeaned so the intercept always refers to the estimate of the average treatment effect, but the coefficients still refer to the average difference in the effectiveness of the advertisement associated with a unit change in the regressor relative to the omitted category.

Candidate favorabilityVote choice
Average effect0.056*0.062*0.0070.008
(0.020)(0.020)(0.007)(0.007)
Democratic respondent
(versus Republican)
0.0350.0220.0110.006
(0.035)(0.036)(0.010)(0.011)
Independent respondent
(versus Republican)
0.0230.0150.0090.007
(0.051)(0.052)(0.020)(0.020)
Battleground state (versus
non-battleground)
−0.00−0.007−0.017−0.017
(0.033)(0.033)(0.010)(0.010)
PAC sponsor (versus
campaign sponsor)
−0.0120.026−0.023−0.016
(0.043)(0.047)(0.013)(0.014)
Time (scaled in months)−0.0230.005−0.009*−0.008
(0.014)(0.010)(0.004)(0.004)
Attack advertisement (versus
promotional
advertisement)
−0.0170.028
(0.046)(0.016)
General election (versus
primary election)
0.123
(0.067)
Pro-Trump advertisement
(versus pro-Clinton
advertisement)
−0.124−0.016
(0.101)(0.034)
Anti-Clinton advertisement
(versus pro-Clinton
advertisement)
−0.1050.012
(0.070)(0.023)
Anti-Trump advertisement
(versus pro-Clinton
advertisement)
−0.0410.026
(0.058)(0.021)
Pro-Sanders advertisement
(versus pro-Clinton
advertisement)
−0.075
(0.089)
Pro-Cruz advertisement
(versus pro-Clinton
advertisement)
0.047
(0.116)
Pro-Kasich advertisement
(versus pro-Clinton
advertisement)
−0.182
(0.145)
Number of observations354354204204

*P < 0.05.