Research ArticleSOCIAL SCIENCES

The small effects of political advertising are small regardless of context, message, sender, or receiver: Evidence from 59 real-time randomized experiments

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Science Advances  02 Sep 2020:
Vol. 6, no. 36, eabc4046
DOI: 10.1126/sciadv.abc4046
  • 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.

    Supplementary Materials

    • Supplementary Materials

      The small effects of political advertising are small regardless of context, message, sender, or receiver: Evidence from 59 real-time randomized experiments

      Alexander Coppock, Seth J. Hill, Lynn Vavreck

      Download Supplement

      This PDF file includes:

      • Treatments
      • Repeat advertisements
      • Analysis of heterogeneity
      • Advertisement transcripts
      • Random assignment
      • Survey questionnaire
      • Tables S1 to S3
      • Fig. S1

      Files in this Data Supplement:

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