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arXiv 1602.01196stat.MEmath.STstat.TH
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使用主得分的主分层分析

Principal stratification analysis using principal scores

Peng Ding, Jiannan Lu

摘要:

从业者感兴趣的不仅是治疗对结果的平均因果效应,而且是在治疗和结果之间存在中间变量的情况下的潜在因果机制。然而,在许多情况下,我们不能随机化中间变量,导致样本选择问题,即使在随机实验。因此,我们将具有中间变量的随机实验视为半观察性研究。在分析观察性研究的同时,我们提供了一个理论基础,进行客观的因果推断与一个中间变量的主要分层框架下,与主要层定义为联合潜在值的中间变量。我们的策略基于主要得分构建加权样本,定义为给定协变量的潜在主要层的条件概率,而无需访问任何结果数据。这种主要分层分析产生了强大的因果推断,而不依赖于任何模型假设的结果分布。我们还提出了方法进行敏感性分析的可验证性和单调性假设,在我们的理论中非常关键的,但不可测试的识别假设的违反。当经典的工具变量分析所需的假设不能被背景知识证明是合理的,或者因为感兴趣的科学问题而不能被证明是合理的时,我们的策略可以作为处理中间变量的一个有用的替代工具。我们用两个真实的数据例子来说明我们的方法,并找到科学上有意义的结论。

英文摘要:

Practitioners are interested in not only the average causal effect of the treatment on the outcome but also the underlying causal mechanism in the presence of an intermediate variable between the treatment and outcome. However, in many cases we cannot randomize the intermediate variable, resulting in sample selection problems even in randomized experiments. Therefore, we view randomized experiments with intermediate variables as semi-observational studies. In parallel with the analysis of observational studies, we provide a theoretical foundation for conducting objective causal inference with an intermediate variable under the principal stratification framework, with principal strata defined as the joint potential values of the intermediate variable. Our strategy constructs weighted samples based on principal scores, defined as the conditional probabilities of the latent principal strata given covariates, without access to any outcome data. This principal stratification analysis yields robust causal inference without relying on any model assumptions on the outcome distributions. We also propose approaches to conducting sensitivity analysis for violations of the ignorability and monotonicity assumptions, the very crucial but untestable identification assumptions in our theory. When the assumptions required by the classical instrumental variable analysis cannot be justified by background knowledge or cannot be made because of scientific questions of interest, our strategy serves as a useful alternative tool to deal with intermediate variables. We illustrate our methodologies by using two real data examples, and find scientifically meaningful conclusions.

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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