The Potential Outcome Framework (POF) plays a prominent role in the field of causal inference. Most causal inference models based on the POF (CIMs-POF) are designed for eliminating confounding bias and default to an underlying assumption of Confounding Covariates. This assumption posits that the covariates consist solely of confounders. However, the assumption of Confounding Covariates is challenging to maintain in practice, particularly when dealing with high-dimensional covariates. While certain methods have been proposed to differentiate the distinct components of covariates prior to conducting causal inference, the consequences of treating non-confounding covariates as confounders remain unclear. This ambiguity poses a potential risk when conducting causal inference in practical scenarios. In this paper, we present a unified graphical framework for the CIMs-POF, which greatly enhances the comprehension of these models' underlying principles. Using this graphical framework, we quantitatively analyze the extent to which the inference performance of CIMs-POF is influenced when incorporating various types of non-confounding covariates, such as instrumental variables, mediators, colliders, and adjustment variables. The key findings are: in the task of eliminating confounding bias, the optimal scenario is for the covariates to exclusively encompass confounders; in the subsequent task of inferring counterfactual outcomes, the adjustment variables contribute to more accurate inferences. Furthermore, extensive experiments conducted on synthetic datasets consistently validate these theoretical conclusions.

翻译：潜在结果框架（POF）在因果推断领域扮演着重要角色。大多数基于POF的因果推断模型（CIMs-POF）旨在消除混杂偏差，并默认遵循“混杂协变量”这一隐含假设。该假设认为协变量仅由混杂变量构成。然而，在实践中，尤其是处理高维协变量时，混杂协变量假设难以维持。尽管已有一些方法提出在实施因果推断前先区分协变量的不同组成部分，但将非混杂协变量视为混杂变量所导致的后果仍不明确。这种模糊性在实际场景中进行因果推断时构成了潜在风险。本文为CIMs-POF提出了一种统一的图形化框架，显著增强了对这些模型基本原理的理解。利用该图形框架，我们定量分析了当纳入工具变量、中介变量、碰撞变量和调整变量等不同类型的非混杂协变量时，CIMs-POF的推断性能受其影响的程度。关键发现如下：在消除混杂偏差的任务中，最优情况是协变量仅包含混杂变量；在后续的反事实结果推断任务中，调整变量有助于实现更准确的推断。此外，在合成数据集上进行的大量实验一致验证了这些理论结论。