Stateful Strategic Regression

TL;DR

This paper models multi-period strategic interactions between decision-makers and agents with internal states, providing algorithms to optimize policies and revealing how repeated interactions influence effort incentives.

Contribution

It introduces a multi-step game framework with internal agent states, characterizes equilibrium, and develops polynomial-time algorithms for policy optimization in this setting.

Findings

Linear assessment policies are as powerful as monotonic policies in this setting.

Polynomial-time algorithms are provided for optimal policy computation.

Multiple interaction rounds enhance the principal's ability to incentivize effort.

Abstract

Automated decision-making tools increasingly assess individuals to determine if they qualify for high-stakes opportunities. A recent line of research investigates how strategic agents may respond to such scoring tools to receive favorable assessments. While prior work has focused on the short-term strategic interactions between a decision-making institution (modeled as a principal) and individual decision-subjects (modeled as agents), we investigate interactions spanning multiple time-steps. In particular, we consider settings in which the agent's effort investment today can accumulate over time in the form of an internal state - impacting both his future rewards and that of the principal. We characterize the Stackelberg equilibrium of the resulting game and provide novel algorithms for computing it. Our analysis reveals several intriguing insights about the role of multiple interactions in shaping the game's outcome: First, we establish that in our stateful setting, the class of all linear assessment policies remains as powerful as the larger class of all monotonic assessment policies. While recovering the principal's optimal policy requires solving a non-convex optimization problem, we provide polynomial-time algorithms for recovering both the principal and agent's optimal policies under common assumptions about the process by which effort investments convert to observable features. Most importantly, we show that with multiple rounds of interaction at her disposal, the principal is more effective at incentivizing the agent to accumulate effort in her desired direction. Our work addresses several critical gaps in the growing literature on the societal impacts of automated decision-making - by focusing on longer time horizons and accounting for the compounding nature of decisions individuals receive over time.