Causal inference in transportation safety studies: comparison of potential outcomes and causal diagrams. (English) Zbl 1223.62175

Summary: The research questions that motivate transportation safety studies are causal in nature. Safety researchers typically use observational data to answer such questions, but often without appropriate causal inference methodology. The field of causal inference presents several modeling frameworks for probing empirical data to assess causal relations. This paper focuses on exploring the applicability of two such modeling frameworks, Causal Diagrams and Potential Outcomes, for a specific transportation safety problem. The causal effects of pavement marking retroreflectivity on safety of a road segment were estimated. More specifically, the results based on three different implementations of these frameworks on a real data set were compared: Inverse Propensity Score Weighting with regression adjustment and Propensity Score Matching with regression adjustment versus Causal Bayesian Network. The effect of increased pavement marking retroreflectivity was generally found to reduce the probability of target nighttime crashes. However, we found that the magnitude of the causal effects estimated are sensitive to the method used and to the assumptions being violated.


62P99 Applications of statistics
62F15 Bayesian inference
65C60 Computational problems in statistics (MSC2010)
68T35 Theory of languages and software systems (knowledge-based systems, expert systems, etc.) for artificial intelligence


gbm; Banjo; twang; TETRAD; BNT
Full Text: DOI arXiv


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