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检测并理解自然中介效应与其随机化干预类似物之间的差异

Detecting and Understanding the Difference between Natural Mediation Effects and Their Randomized Interventional Analogues

Ang Yu, Li Ge, Felix Elwert

AI总结:

本文提出首个经验检验方法,用于在弱假设下检测自然中介效应与其随机化干预类似物(RIAs)之间的差异,并从协方差和结构方程视角阐明二者关系,揭示其与工具变量分析及Wilcoxon-Mann-Whitney检验估计目标的联系。

摘要:

在因果中介分析中,自然直接效应和自然间接效应(自然效应)在存在治疗诱发混杂的情况下是非参数不可识别的,这推动了自然效应的随机化干预类似物(RIAs)的发展。由于更易于识别,RIAs在实践中正被广泛使用。然而,应用研究者常常将RIA估计值解释为自然效应,尽管RIAs可能是自然效应的较差替代。这要求就RIAs何时与自然效应不同或一致提供实践和理论指导。我们开发了第一个经验检验方法,在足以识别RIAs的弱假设下检测自然效应与其RIAs之间的差异,并使用“向机遇迁移研究”(Moving to Opportunity Study)对该检验进行了说明。我们还通过协方差公式和结构方程视角,对自然效应与RIAs之间的关系提供了新的理论见解。该分析还揭示了自然效应、RIAs以及工具变量分析和Wilcoxon-Mann-Whitney检验中的估计目标之间此前未被记载的联系。

英文摘要:

In causal mediation analysis, the natural direct and indirect effects (natural effects) are nonparametrically unidentifiable in the presence of treatment-induced confounding, which motivated the development of randomized interventional analogues (RIAs) of the natural effects. Being easier to identify, the RIAs are becoming widely used in practice. However, applied researchers often interpret RIA estimates as if they were the natural effects, even though the RIAs can be poor proxies for the natural effects. This calls for practical and theoretical guidance on when the RIAs differ from or coincide with the natural effects. We develop the first empirical test to detect the divergence between the natural effects and their RIAs under the weak assumptions sufficient for identifying the RIAs and illustrate the test using the Moving to Opportunity Study. We also provide new theoretical insights on the relationship between the natural effects and the RIAs both using a covariance formulation and from a structural equation perspective. This analysis also reveals previously undocumented connections between the natural effects, the RIAs, and estimands in instrumental variable analysis and Wilcoxon-Mann-Whitney tests.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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