Researchers have long debated how radio broadcasts affected the dynamics of the 1994 genocide in Rwanda, with some arguing that the radio was highly consequential, and others suggesting such effects have been overstated. This article contributes to these debates—as well as to debates regarding the role of old and new media in collective action—by examining whether and how Radio Télévision Libre des Mille Collines (Radio RTLM) coverage was associated with two core aspects of the violence: (1) subnational onset of genocidal violence and (2) participation in genocidal violence across subnational spaces. Drawing on new data on Radio RTLM coverage, we find that areas with coverage were more likely to experience immediate onset of violence. However, our analysis of participation in the genocide—which uses more accurate measures of participation and of radio coverage than prior studies—finds no significant association between Radio RTLM coverage and subnational levels of participation. After illustrating that these results are robust to numerous model specifications, we theorize that information broadcast over the radio’s airways contributed to the creation of a critical mass that initiated genocide in localized spaces. We conclude by considering the importance of understanding the role of media in the subnational onset of violence.

The test-negative design (TND) has become a standard approach to evaluate vaccine effectiveness against the risk of acquiring infectious diseases in real-world settings, such as Influenza, Rotavirus, Dengue fever, and more recently COVID-19. In a TND study, individuals who experience symptoms and seek care are recruited and tested for the infectious disease which defines cases and controls. Despite TND’s potential to reduce unobserved differences in healthcare seeking behavior (HSB) between vaccinated and unvaccinated subjects, it remains subject to various potential biases. First, residual confounding may remain due to unobserved HSB, occupation as healthcare worker, or previous infection history. Second, because selection into the TND sample is a common consequence of infection and HSB, collider stratification bias may exist when conditioning the analysis on tested samples, which further induces confounding by latent HSB. In this article, we present a novel approach to identify and estimate vaccine effectiveness in the target population by carefully leveraging a pair of negative control exposure and outcome variables to account for potential hidden bias in TND studies. We illustrate our proposed method with extensive simulations and an application to study COVID-19 vaccine effectiveness using data from the University of Michigan Health System. Supplementary materials for this article are available online.