Title: Personalized policy learning using longitudinal mobile health data
Authors: Ken Cheung - Columbia University (United States) [presenting]
Xinyu Hu - Uber (United States)
Min Qian - Columbia University (United States)
Bin Cheng - Columbia University (United States)
Abstract: The personalized policy learning problem is addressed by using longitudinal mobile health application usage data. Personalized policy represents a paradigm shift from developing a single policy that may prescribe personalized decisions by tailoring. Specifically, we aim to develop the best policy, one per user, based on estimating random effects under a generalized linear mixed model. With many random effects, we consider new estimation method and penalized objective to circumvent high-dimension integrals for marginal likelihood approximation. We establish consistency and optimality of our method with endogenous app usage. We apply the method to develop personalized push (prompt) schedules in 294 app users, intending to maximize the prompt response rate given past app usage and other contextual factors. We found the best push schedule given the same covariates varied among the users, thus calling for personalized policies. Using the estimated personalized policies would have achieved a mean prompt response rate of 23\% in these users at 16 weeks or later: this is a remarkable improvement on the observed rate (11\%), while the literature suggests 3\%-15\% user engagement at 3 months after download. The proposed method compares favorably to existing estimation methods, including using the R function glmer in a simulation study.