Coarse Personalization

Abstract: With advances in estimating heterogeneous treatment effects, firms can personalize and target individuals at a granular level. However, feasibility constraints limit full personalization. In practice, firms choose segments of individuals and assign a treatment to each segment to maximize profits: We call this the coarse personalization problem. We propose a two-step solution that simultaneously makes segmentation and targeting decisions. First, the firm personalizes by estimating conditional average treatment effects. Second, the firm discretizes using treatment effects to choose which treatments to offer and their segments. We show that a combination of available machine learning tools for estimating heterogeneous treatment effects and a novel application of optimal transport methods provides a viable and efficient solution. With data from a large-scale field experiment in promotions management, we find our methodology outperforms extant approaches that segment on consumer characteristics, consumer preferences, or those that only search over a prespecified grid. Using our procedure, the firm recoups over $99.5\%$ of its expected incremental profits under full personalization while offering only five segments. We conclude by discussing how coarse personalization arises in other domains.