Testability of Instrumental Variables in Linear Non-Gaussian Acyclic Causal Models

Autor: Feng Xie, Yangbo He, Zhi Geng, Zhengming Chen, Ru Hou, Kun Zhang
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Entropy, Vol 24, Iss 4, p 512 (2022)
Druh dokumentu: article
ISSN: 1099-4300
DOI: 10.3390/e24040512
Popis: This paper investigates the problem of selecting instrumental variables relative to a target causal influence X→Y from observational data generated by linear non-Gaussian acyclic causal models in the presence of unmeasured confounders. We propose a necessary condition for detecting variables that cannot serve as instrumental variables. Unlike many existing conditions for continuous variables, i.e., that at least two or more valid instrumental variables are present in the system, our condition is designed with a single instrumental variable. We then characterize the graphical implications of our condition in linear non-Gaussian acyclic causal models. Given that the existing graphical criteria for the instrument validity are not directly testable given observational data, we further show whether and how such graphical criteria can be checked by exploiting our condition. Finally, we develop a method to select the set of candidate instrumental variables given observational data. Experimental results on both synthetic and real-world data show the effectiveness of the proposed method.
Databáze: Directory of Open Access Journals
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