Taking Uncertainty Seriously: Bayesian Marginal Structural Models for Causal Inference in Political Science
The past two decades have been characterized by considerable progress in developing approaches to causal inference in situations where true experimental manipulation is either impractical or impossible. With few exceptions, however, commonly employed techniques in political science have developed largely within a frequentist framework (i.e., Blackwell and Glynn 2018; Imai and Kim 2019; Torres 2020). In this article, we argue that common approaches rest fundamentally upon assumptions that are difficult to defend in many areas of political research and highlight the benefits of quantifying uncertainty in the estimation of causal effects (Gill 1999; Gill and Heuberger 2020; Schrodt 2014; Western and Jackman 1994). Extending the approach to causal inference for cross-sectional time series and panel data under selection on observables introduced by Blackwell and Glynn (2018), we develop a two-step pseudo-Bayesian method for estimating marginal structural models. We demonstrate our proposed procedure in the context linear mixed effects models via a simulation study and two empirical examples. Finally, we provide flexible open-source software implementing the proposed method.
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Blackwell, Matthew, and Adam N. Glynn. 2018. “How to Make Causal Inferences with Time-Series Cross-Sectional Data Under Selection on Observables.” American Political Science Review 112: 1067–82.
Gill, Jeff. 1999. “The Insignificance of Null Hypothesis Significance Testing.” Political Research Quarterly 52: 647–74.
Gill, Jeff, and Simon Heuberger. 2020. “Bayesian Modeling and Inference: A Post-Modern Perspective.” In The SAGE Handbook of Research Methods in Political Science and International Relations, eds. Luigi Curini and Robert Franzese. London, UK: SAGE, 961–84.
Imai, Kosuke, and In Song Kim. 2019. “When Should We Use Unit Fixed Effects Regression Models for Causal Inference with Longitudinal Data?” American Journal of Political Science 63(2): 467–90.
Schrodt, Philip A. 2014. “Seven Deadly Sins of Contemporary Quantitative Political Analysis.” Journal of Peace Research 51: 287–300.
Torres, Michelle. 2020. “Estimating Controlled Direct Effects Through Marginal Structural Models.” Political Science Research and Methods 8(3): 391–408.
Western, Bruce, and Simon Jackman. 1994. “Bayesian Inference for Comparative Research.” American Political Science Review 88: 412–23.