论文标题
在随时间变化的中介模型中的调解效应的估计和推断
Estimation and Inference for the Mediation Effect in a Time-varying Mediation Model
论文作者
论文摘要
传统的调解分析通常检查干预措施，时间不变的调解人和时间不变的结果变量之间的关系。尽管干预对结果可能有直接影响，但有必要了解干预措施影响结果的过程（即通过调解人的间接效应）。这种间接效应通常被认为是时间不变的。随着数据收集技术的改进，可以随着时间的推移获得重复的评估，从而产生密集的纵向数据。这要求扩展传统的调解分析以结合时变变量以及时变效果。在本文中，我们着重于对时变调解模型的估计和推断，该模型允许调解效应随时间的变化而变化。我们提出了一种两步方法来估计随时间变化的调解效果。此外，我们使用基于模拟的方法来得出相应的点置信带，以实现随时间变化的调解效果。模拟研究表明，在比较置信带和真实的基础模型时，提出的程序表现良好。我们进一步将提出的模型和统计推断程序应用于从戒烟研究中收集的现实数据。
Traditional mediation analysis typically examines the relations among an intervention, a time-invariant mediator, and a time-invariant outcome variable. Although there may be a direct effect of the intervention on the outcome, there is a need to understand the process by which the intervention affects the outcome (i.e. the indirect effect through the mediator). This indirect effect is frequently assumed to be time-invariant. With improvements in data collection technology, it is possible to obtain repeated assessments over time resulting in intensive longitudinal data. This calls for an extension of traditional mediation analysis to incorporate time-varying variables as well as time-varying effects. In this paper, we focus on estimation and inference for the time-varying mediation model, which allows mediation effects to vary as a function of time. We propose a two-step approach to estimate the time-varying mediation effect. Moreover, we use a simulation based approach to derive the corresponding point-wise confidence band for the time-varying mediation effect. Simulation studies show that the proposed procedures perform well when comparing the confidence band and the true underlying model. We further apply the proposed model and the statistical inference procedure to real-world data collected from a smoking cessation study.
