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Bias in Political Communication Experiments (WP-10-10)

James Druckman and Thomas Leeper

Research on political communication effects has enjoyed great progress over the past 20 years. A key ingredient underlying these advances is the increased usage of experiments that demonstrate how communications influence opinions and behaviors. A potential problem with nearly all of these studies, however, concerns the lack of attention to events that occur prior to the experiment—that is, “pretreatment events.” In this paper, the authors explore how and when the pretreatment environment affects experimental outcomes. They argue that ignoring pretreatment has led extant work to overstate the malleability of the mass public, miss the identification of potentially two groups of voters—what they call malleability reactive and dogmatic—and contradict macro level work on aggregate public opinion trends.

James Druckman, Payson S. Wild Professor in Political Science and Faculty Fellow, Institute for Policy Research, Northwestern University

Thomas Leeper, Doctoral Student in Political Science and Faculty Graduate Research Assistant, Institute for Policy Research, Northwestern University

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