论文标题
在混淆依赖性取样下的双重稳健近端因果推断
Doubly Robust Proximal Causal Inference under Confounded Outcome-Dependent Sampling
论文作者
论文摘要
在观察性研究中,经常关注未衡量的混杂和选择偏见,如果不适当地解释因果分析。在结果依赖性抽样的情况下,对治疗,结果和样本选择过程有因果影响的潜在因素可能会导致无法测量的混杂和选择偏见,从而使标准因果参数无法识别而没有其他假设。在治疗效果的优势比模型下,Li等人。 2022年通过利用一对阴性对照变量作为混杂和选择偏见来源的潜在因素的代理来建立近端鉴定和因果效应的估计。但是,他们的方法仅依赖于所谓的治疗混淆桥梁功能的存在和正确规范,该模型限制了治疗分配机制。在本文中,我们提出了相对于两个滋扰函数的几率比值模型下的双重稳定估计 - 处理桥梁功能的混淆和结果混淆桥梁功能限制了结果定律,使我们的估计器保持一致且如果任何桥梁函数模型正确地指定了哪个桥梁,则估计器在不知道的情况下是不正常的。因此,我们提出的双重稳健估计量可能比Li等人更强大。 2022年。我们的模拟证实,在既定情况下,在标准方法中,标准方法通常无法保持一致的情况下,拟议条件下,提出的近端估计值可以充分说明残留混淆和选择偏差,并在各种场景中均具有良好的置信区间。另外,如果正确指定了至少一个混淆桥功能,则提出的双重稳健估计器是一致的。
Unmeasured confounding and selection bias are often of concern in observational studies and may invalidate a causal analysis if not appropriately accounted for. Under outcome-dependent sampling, a latent factor that has causal effects on the treatment, outcome, and sample selection process may cause both unmeasured confounding and selection bias, rendering standard causal parameters unidentifiable without additional assumptions. Under an odds ratio model for the treatment effect, Li et al. 2022 established both proximal identification and estimation of causal effects by leveraging a pair of negative control variables as proxies of latent factors at the source of both confounding and selection bias. However, their approach relies exclusively on the existence and correct specification of a so-called treatment confounding bridge function, a model that restricts the treatment assignment mechanism. In this article, we propose doubly robust estimation under the odds ratio model with respect to two nuisance functions -- a treatment confounding bridge function and an outcome confounding bridge function that restricts the outcome law, such that our estimator is consistent and asymptotically normal if either bridge function model is correctly specified, without knowing which one is. Thus, our proposed doubly robust estimator is potentially more robust than that of Li et al. 2022. Our simulations confirm that the proposed proximal estimators of an odds ratio causal effect can adequately account for both residual confounding and selection bias under stated conditions with well-calibrated confidence intervals in a wide range of scenarios, where standard methods generally fail to be consistent. In addition, the proposed doubly robust estimator is consistent if at least one confounding bridge function is correctly specified.