Optimal Treatment Regimes for Proximal Causal Learning

Tao Shen, Yifan Cui

Keywords: Optimal treatment regimes, Policy-making, Proximal causal inference, Unmeasured confounding, Value function

TL;DR: This paper developes the sharpest individualized decision-making for recently proposed proximal causal learning

Abstract: A common concern when a policymaker draws causal inferences from and makes decisions based on observational data is that the measured covariates are insufficiently rich to account for all sources of confounding, i.e., the standard no confoundedness assumption fails to hold. The recently proposed proximal causal inference framework shows that proxy variables that abound in real-life scenarios can be leveraged to identify causal effects and therefore facilitate decision-making. Building upon this line of work, we propose a novel optimal individualized treatment regime based on so-called outcome and treatment confounding bridges. We then show that the value function of this new optimal treatment regime is superior to that of existing ones in the literature. Theoretical guarantees, including identification, superiority, excess value bound, and consistency of the estimated regime, are established. Furthermore, we demonstrate the proposed optimal regime via numerical experiments and a real data application.

Submission Number: 2628