Ratio-of-Mediator-Probability Weighting for Causal Mediation Analysis in the Presence of Treatment-by-Mediator Interaction
Ratio-of-Mediator-Probability Weighting for Causal Mediation Analysis in the Presence of Treatment-by-Mediator Interaction
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DOI：
10.3102/1076998615583902
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发表时间：
2015-06-01
影响因子：
2.4
通讯作者：
Hill, Heather D.
中科院分区：
文献类型：
--
作者：
Hong, Guanglei;Deutsch, Jonah;Hill, Heather D.
当中介-结果关系取决于治疗条件时，传统的中介分析方法会产生偏倚的结果。本文展示了如何使用中介概率加权比率（RMPW）方法，在存在中介相互作用的情况下，将总效应分解为自然的直接效应和间接效应。间接效应可以进一步分解为纯粹的间接效应和自然的中介处理相互作用效应。与其他因果中介分析技术类似，当顺序可忽略性假设成立时，RMPW生成因果有效的结果。然而，与基于模型的替代方法（包括路径分析、结构方程建模及其最新扩展）不同，RMPW对结果的分布、中介的分布和结果模型的功能形式要求相对较少的假设。当应用参数RMPW时，对中介的倾向评分模型的正确规范仍然是至关重要的。本文给出了RMPW原理的直观解释、数学证明以及参数化和非参数化RMPW过程的仿真结果。我们应用该技术来确定就业是否介导了实验性福利工作计划与母亲抑郁之间的关系。分析过程的详细描述伴随着在线Stata代码以及独立的RMPW软件程序，以方便用户的分析决策。
Conventional methods for mediation analysis generate biased results when the mediator-outcome relationship depends on the treatment condition. This article shows how the ratio-of-mediator-probability weighting (RMPW) method can be used to decompose total effects into natural direct and indirect effects in the presence of treatment-by-mediator interactions. The indirect effect can be further decomposed into a pure indirect effect and a natural treatment-by-mediator interaction effect. Similar to other techniques for causal mediation analysis, RMPW generates causally valid results when the sequential ignorability assumptions hold. Yet unlike the model-based alternatives, including path analysis, structural equation modeling, and their latest extensions, RMPW requires relatively few assumptions about the distribution of the outcome, the distribution of the mediator, and the functional form of the outcome model. Correct specification of the propensity score models for the mediator remains crucial when parametric RMPW is applied. This article gives an intuitive explanation of the RMPW rationale, a mathematical proof, and simulation results for the parametric and nonparametric RMPW procedures. We apply the technique to identifying whether employment mediated the relationship between an experimental welfare-to-work program and maternal depression. A detailed delineation of the analytic procedures is accompanied by online Stata code as well as a stand-alone RMPW software program to facilitate users' analytic decision making.