Working paper, with Michael Jetsupphasuk; an earlier version of the paper is entitled "Causal Inference under Temporal and Spatial Interference." Download the manuscript here Why this paper matters Longitudinal causal inference in biostatistics, epidemiology, and social sciences often relies on marginal structural models (MSMs), which summarize the effects of time-varying treatments and can be consistently estimated using inverse probability weighting (IPW) under sequential

PNAS 2023, with Ruixue Jia , Margaret Roberts , and Eddie Yang Download the manuscript here This paper documents how U.S.–China political tensions have reshaped scientific production in the United States. We study NIH-initiated investigations that began in 2018 and targeted undisclosed foreign funding, with most cases involving China. Using large-scale publication data from 2010–2021, we compare U.S. life scientists who had collaborated with researchers in China to similar s

Annals of Applied Statistics, 2025, with Cyrus Samii , Haoge Chang, and P Aronow . Why this paper matters Many policy experiments and field interventions, such as forest conservation programs, public health campaigns, and policing deployments, take place in geographic space. In these settings, treatment at one location can affect outcomes nearby, creating spatial interference that violates the stable unit treatment value assumption (SUTVA). Existing solutions to this proble

Political Analysis, 2025, with Cyrus Samii and Junlong Aaron Zhou . Why this problem matters Many experiments and quasi-experiments suffer from the problem of endogenously missing outcomes : researchers only observe results for people who complete a key task, such as a survey, conversation, or interview, while dropout or nonresponse itself can be affected by the treatment. This creates what Slough (2023) calls the “phantom counterfactual” issue, where some units have undef

Electoral Studies, 2021 , with Stan Wong Download the manuscript here This paper examines how a major anti-regime protest—the 2014 Umbrella Movement in Hong Kong—shaped electoral outcomes in the city. Using fine-grained constituency-level election data, we show that citizens living closer to the protest sites were more likely to shift away from the pro-democracy opposition in the subsequent legislative election. A one–standard deviation decrease in distance to the protest sit