The (In)Effectiveness of Political Advertising in Canada: A Conceptual Replication

Abstract In an effort to conceptually replicate prior work on persuasion and campaign effects, we conducted three randomized survey experiments to evaluate the persuasive effects of political advertisements during the 2025 Canadian federal election. We tested a total of 15 campaign advertisements on 3,346 respondents. Our results are consistent with what seems to be three robust findings about the effects of campaign advertising: (1) they can change candidate evaluations and vote intentions, but (2) the effects are very small, and most importantly, (3) persuasive treatment effects seem to be mostly homogeneous. We offer new empirical evidence that strengthens previous findings on the homogeneity of persuasive treatment effects of political advertising in Canada that challenges the extent to which microtargeting improves candidates and advocacy groups’ ability to sway public opinion.