arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2308.03369stat.ML
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因果森林的变量重要性:分解处理效应的异质性

Variable importance for causal forests: breaking down the heterogeneity of treatment effects

Clément Bénard, Julie Josse

AI总结:

本文针对因果森林的黑箱局限,提出一种基于“丢弃并重新学习”原则的变量重要性算法,用于量化各输入对处理效应异质性的影响,并通过修正项处理混杂变量,实验证明其性能优于竞争方法且可扩展到变量组。

摘要:

因果随机森林能够高效估计异质性处理效应。然而,森林算法也因其黑箱特性而广为人知,因此无法刻画输入变量如何参与处理效应异质性,这构成了一个很强的实际局限。在本文中,我们为因果森林开发了一种新的变量重要性算法,用于量化每个输入对处理效应异质性的影响。所提出的方法受到“丢弃并重新学习”(drop and relearn)原则的启发,该原则广泛用于回归问题。重要的是,我们展示了如何在没有混杂变量的情况下处理森林的重新训练。如果混杂变量不参与处理效应异质性,局部中心化步骤能够保证重要性度量的一致性。否则,当混杂变量同时影响异质性时,我们在重新训练的因果森林中引入一个修正项以恢复一致性。此外,在模拟数据、半合成数据和真实数据上的实验表明,我们的重要性度量具有良好的性能,在多个测试案例上优于竞争方法。实验还表明,我们的方法可以高效地扩展到变量组,从而在实践中提供关键洞见。

英文摘要:

Causal random forests provide efficient estimates of heterogeneous treatment effects. However, forest algorithms are also well-known for their black-box nature, and therefore, do not characterize how input variables are involved in treatment effect heterogeneity, which is a strong practical limitation. In this article, we develop a new importance variable algorithm for causal forests, to quantify the impact of each input on the heterogeneity of treatment effects. The proposed approach is inspired from the drop and relearn principle, widely used for regression problems. Importantly, we show how to handle the forest retrain without a confounding variable. If the confounder is not involved in the treatment effect heterogeneity, the local centering step enforces consistency of the importance measure. Otherwise, when a confounder also impacts heterogeneity, we introduce a corrective term in the retrained causal forest to recover consistency. Additionally, experiments on simulated, semi-synthetic, and real data show the good performance of our importance measure, which outperforms competitors on several test cases. Experiments also show that our approach can be efficiently extended to groups of variables, providing key insights in practice.

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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