Given a binary treatment and a binary mediator, mediation analysis decomposes the total effect of the treatment on an outcome variable into direct and indirect effects. However, the existing decompositions are "path-dependent", and consequently, there appeared different versions of direct and indirect effects. Differently from these, this paper proposes a "path-free" decomposition of the total effect into three sub-effects: direct, indirect, and treatment-mediator interaction effects. Whereas the interaction effect has been part of the indirect effect in the existing two-effect decompositions, it is separately identified in our three-effect decomposition. All effects are found using conditional means, but not conditional densities, and are estimated with ordinary least squares estimators. Simulation and empirical analyses are provided as well.
翻译:考虑到二元治疗和二元调解人,调解分析将治疗对结果变量的总体影响分解为直接和间接影响,然而,现有的分解是“依赖病理”的,因此出现了直接和间接影响的不同版本。与此不同的是,本文件建议“无病理”将总影响分解为三种副影响:直接、间接和治疗-调解互动效应。虽然互动效应是现有两种影响分解中间接影响的一部分,但在我们三种影响分解中单独识别。所有影响都使用有条件手段,但并非有条件密度,并且用普通最低的方位估计值估算。提供了模拟和实证分析。