论文标题
安慰剂样品在观测研究中的作用
The Role of Placebo Samples in Observational Studies
论文作者
论文摘要
在一项观察性研究中，通常利用已知的无效效应来检测偏差。一种这样的策略是搁置安慰剂样本 - 一部分数据免疫免受假设的因果关系。安慰剂样本中的效果的存在引起了人们对缺乏混杂偏见的关注，而缺乏偏见可以证实因果关系。本文建立了一个正式的框架，用于使用安慰剂样品检测和消除偏见。我们根据结果回归，概率加权和双重稳定方法来陈述识别假设，并开发估计和推理方法。仿真研究和经验应用说明了所提出方法的有限样本性能。
In an observational study, it is common to leverage known null effect to detect bias. One such strategy is to set aside a placebo sample -- a subset of data immune from the hypothesized cause-and-effect relationship. Existence of an effect in the placebo sample raises concern of unmeasured confounding bias while absence of it corroborates the causal conclusion. This paper establishes a formal framework for using a placebo sample to detect and remove bias. We state identification assumption, and develop estimation and inference methods based on outcome regression, inverse probability weighting, and doubly-robust approaches. Simulation studies and an empirical application illustrate the finite-sample performance of the proposed methods.
