Double Machine Learning for Causal Inference under Shared-State Interference
This work addresses causal inference challenges for researchers and practitioners in interactive environments like social networks and algorithmic systems, though it appears incremental as it extends existing DML methods to a new interference setting.
The paper tackles the problem of measuring treatment effects in settings with shared-state interference, such as markets and recommendation systems, by formalizing this structure and proving an extension of a double machine learning theorem that enables efficient inference for average direct and global average treatment effects.
Researchers and practitioners often wish to measure treatment effects in settings where units interact via markets and recommendation systems. In these settings, units are affected by certain shared states, like prices, algorithmic recommendations or social signals. We formalize this structure, calling it shared-state interference, and argue that our formulation captures many relevant applied settings. Our key modeling assumption is that individuals' potential outcomes are independent conditional on the shared state. We then prove an extension of a double machine learning (DML) theorem providing conditions for achieving efficient inference under shared-state interference. We also instantiate our general theorem in several models of interest where it is possible to efficiently estimate the average direct effect (ADE) or global average treatment effect (GATE).