Developing interventions that successfully reduce engagement with misinformation on social media is challenging. One intervention that has recently gained great attention is Twitter's Community Notes (previously known as "Birdwatch"). Community Notes is a crowdsourced fact-checking approach that allows users to write textual notes to inform others about potentially misleading posts on Twitter. Yet, empirical evidence regarding its effectiveness in reducing engagement with misinformation on social media is missing. In this paper, we perform a large-scale empirical study to analyze whether the introduction of the Community Notes feature and its roll-out to users in the U. S. and around the world have reduced engagement with misinformation on Twitter in terms of retweet volume and likes. We employ Difference-in-Difference (DiD) models and Regression Discontinuity Design (RDD) to analyze a comprehensive dataset consisting of all fact-checking notes and corresponding source tweets since the launch of Community Notes in early 2021. Although we observe a significant increase in the volume of fact-checks carried out via Community Notes, particularly for tweets from verified users with many followers, we find no evidence that the introduction of Community Notes significantly reduced engagement with misleading tweets on Twitter. Rather, our findings suggest that Community Notes might be too slow to effectively reduce engagement with misinformation in the early (and most viral) stage of diffusion. Our work emphasizes the importance of evaluating fact-checking interventions in the field and offers important implications to enhance crowdsourced fact-checking strategies on social media.

翻译：开发能够有效减少社交媒体上虚假信息参与度的干预措施具有挑战性。近期备受关注的一项干预措施是推特的社区笔记（原名“Birdwatch”）。社区笔记是一种众包事实核查方法，允许用户撰写文字说明，以告知他人推特上可能具有误导性的帖子。然而，目前尚缺乏关于其在减少社交媒体虚假信息参与度方面有效性的实证证据。本文通过大规模实证研究，分析社区笔记功能的引入及其向美国及全球用户的推广，是否从转发量和点赞数角度减少了推特上虚假信息的参与度。我们采用双重差分模型和断点回归设计，分析了自2021年初社区笔记推出以来所有事实核查笔记及相应源推文的综合数据集。尽管观察到通过社区笔记进行的事实核查量显著增加（尤其是针对拥有大量粉丝的认证用户的推文），但我们未发现任何证据表明社区笔记的引入显著减少了推特上误导性推文的参与度。相反，我们的研究结果表明，社区笔记在虚假信息扩散的早期（且最具病毒性传播潜力的）阶段可能过于迟缓，无法有效减少其参与度。本研究强调了在真实场景中评估事实核查干预措施的重要性，并为优化社交媒体上的众包事实核查策略提供了重要启示。