论文标题

有针对性的最大似然估计社区级随机干预措施的基于社区的因果关系

Targeted Maximum Likelihood Estimation of Community-based Causal Effect of Community-Level Stochastic Interventions

论文作者

Zhang, Chi, Ahern, Jennifer, van der Laan, Mark J.

论文摘要

与常用的参数回归模型(例如混合模型)不同,这些模型可以轻松违反所需的统计假设并导致无效的统计推断,目标最大似然估计允许更真实的数据产生模型并提供双重射击,半参数和有效的估计器。 Balzer等人先前提出了针对社区水平静态暴露的因果效应的目标最大似然估计器(TMLE)。在此手稿中,我们以这项工作为基础并提供可识别性结果,并开发了两个半参数有效的TMLE,以估算单个时间点社区级随机干预的因果效应,其分配机制可以取决于测量和未衡量的环境因素及其个体级别的协方差。第一个社区级别的TMLE是在一般分层的非参数结构方程模型下开发的,该模型可以结合汇总的个人级别回归来估算结果机制。第二个个人级别的TMLE是在受限制的层次模型下开发的,在该模型中,社区内无协变量干扰的附加假设。拟议的TMLE具有几个至关重要的优势。首先,两个TMLE都可以在层次结构中使用单个级别数据,并有可能降低有限的样本偏差并提高估计器效率。其次,随机干预框架提供了一种自然的方法来定义和估计休闲效果,而暴露变量是连续或离散的,具有多个级别的连续或离散,甚至无法直接介入。同样,我们提出的因果参数所需的阳性假设可能比其他休闲参数所需的阳性版本弱。

Unlike the commonly used parametric regression models such as mixed models, that can easily violate the required statistical assumptions and result in invalid statistical inference, target maximum likelihood estimation allows more realistic data-generative models and provides double-robust, semi-parametric and efficient estimators. Target maximum likelihood estimators (TMLEs) for the causal effect of a community-level static exposure were previously proposed by Balzer et al. In this manuscript, we build on this work and present identifiability results and develop two semi-parametric efficient TMLEs for the estimation of the causal effect of the single time-point community-level stochastic intervention whose assignment mechanism can depend on measured and unmeasured environmental factors and its individual-level covariates. The first community-level TMLE is developed under a general hierarchical non-parametric structural equation model, which can incorporate pooled individual-level regressions for estimating the outcome mechanism. The second individual-level TMLE is developed under a restricted hierarchical model in which the additional assumption of no covariate interference within communities holds. The proposed TMLEs have several crucial advantages. First, both TMLEs can make use of individual level data in the hierarchical setting, and potentially reduce finite sample bias and improve estimator efficiency. Second, the stochastic intervention framework provides a natural way for defining and estimating casual effects where the exposure variables are continuous or discrete with multiple levels, or even cannot be directly intervened on. Also, the positivity assumption needed for our proposed causal parameters can be weaker than the version of positivity required for other casual parameters.

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