Hierarchical Contextual Uplift Bandits for Catalog Personalization
This addresses the problem of frequent retraining needs in dynamic recommendation systems for fantasy sports platforms, representing an incremental improvement.
The paper tackled the challenge of personalizing recommendations in dynamic environments like fantasy sports by proposing a Hierarchical Contextual Uplift Bandit framework, which achieved a 0.4% revenue improvement in A/B testing and a further 0.5% after deployment.
Contextual Bandit (CB) algorithms are widely adopted for personalized recommendations but often struggle in dynamic environments typical of fantasy sports, where rapid changes in user behavior and dramatic shifts in reward distributions due to external influences necessitate frequent retraining. To address these challenges, we propose a Hierarchical Contextual Uplift Bandit framework. Our framework dynamically adjusts contextual granularity from broad, system-wide insights to detailed, user-specific contexts, using contextual similarity to facilitate effective policy transfer and mitigate cold-start issues. Additionally, we integrate uplift modeling principles into our approach. Results from large-scale A/B testing on the Dream11 fantasy sports platform show that our method significantly enhances recommendation quality, achieving a 0.4% revenue improvement while also improving user satisfaction metrics compared to the current production system. We subsequently deployed this system to production as the default catalog personalization system in May 2025 and observed a further 0.5% revenue improvement.