Bayesian Model Averaging in Causal Instrumental Variable Models

Fuente: arXiv
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Autores principales: Steiner, Gregor, Steel, Mark
Formato: Preprint
Publicado: 2025
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author Steiner, Gregor
Steel, Mark
author_facet Steiner, Gregor
Steel, Mark
contents Instrumental variables are a popular tool to infer causal effects under unobserved confounding, but choosing suitable instruments is challenging in practice. We propose gIVBMA, a Bayesian model averaging procedure that addresses this challenge by averaging across different sets of instrumental variables and covariates in a structural equation model. This allows for data-driven selection of valid and relevant instruments and provides additional robustness against invalid instruments. Our approach extends previous work through a scale-invariant prior structure and accommodates non-Gaussian outcomes and treatments, offering greater flexibility than existing methods. The computational strategy uses conditional Bayes factors to update models separately for the outcome and treatments. We prove that this model selection procedure is consistent. In simulation experiments, gIVBMA outperforms current state-of-the-art methods. We demonstrate its usefulness in two empirical applications: the effects of malaria and institutions on income per capita and the returns to schooling. A software implementation of gIVBMA is available in Julia.
format Preprint
id arxiv_https___arxiv_org_abs_2504_13520
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bayesian Model Averaging in Causal Instrumental Variable Models
Steiner, Gregor
Steel, Mark
Methodology
Econometrics
Statistics Theory
Instrumental variables are a popular tool to infer causal effects under unobserved confounding, but choosing suitable instruments is challenging in practice. We propose gIVBMA, a Bayesian model averaging procedure that addresses this challenge by averaging across different sets of instrumental variables and covariates in a structural equation model. This allows for data-driven selection of valid and relevant instruments and provides additional robustness against invalid instruments. Our approach extends previous work through a scale-invariant prior structure and accommodates non-Gaussian outcomes and treatments, offering greater flexibility than existing methods. The computational strategy uses conditional Bayes factors to update models separately for the outcome and treatments. We prove that this model selection procedure is consistent. In simulation experiments, gIVBMA outperforms current state-of-the-art methods. We demonstrate its usefulness in two empirical applications: the effects of malaria and institutions on income per capita and the returns to schooling. A software implementation of gIVBMA is available in Julia.
title Bayesian Model Averaging in Causal Instrumental Variable Models
topic Methodology
Econometrics
Statistics Theory
url https://arxiv.org/abs/2504.13520