Experimentation under Treatment Dependent Network Interference

Shiv Shankar, Ritwik Sinha, Madalina Fiterau

Keywords: a/b testing, treatment effect, interference

TL;DR: We present methods to estimate treatment effects under treatment dependent interference.

Abstract:

Randomized Controlled Trials (RCTs) are a fundamental aspect of data-driven decision-making. RCTs often assume that the units are not influenced by each other.
Traditional approaches addressing such effects assume a fixed network structure between the interfering units. However, real-world networks are rarely static, and treatment assignments can actively reshape the interference structure itself, as seen in financial access interventions that alter informal lending networks or healthcare programs that modify peer influence dynamics. This creates a novel and unexplored problem: estimating treatment effects when the interference network is determined by treatment allocation.
In this work, we address this gap by proposing two single-experiment estimators for scenarios where network edges depend on nodal treatments constructed from instrumental variables derived from neighbourhood treatments. We prove their unbiasedness and experimentally validate the proposed estimators both on synthetic and real data.

Code Link: https://github.com/sshivs/ivgate

Readers: auai.org/UAI/2025/Conference, auai.org/UAI/2025/Conference/Area_Chairs, auai.org/UAI/2025/Conference/Reviewers, auai.org/UAI/2025/Conference/Submission414/Authors, auai.org/UAI/2025/Conference/Submission414/Reproducibility_Reviewers

Submission Number: 414