Evaluation
All of Spotify’s research and engineering effort depends on metrics, experimentation, and evaluation, both online and offline. Research in online testing is essential for deploying tests and interpreting results. Research in offline testing is important at Spotify for its influence on models and A/B test decisions, and range from using offline test collections, historical log data, counterfactual analysis, and metrics developed using mixed quantitative and qualitative methods approaches to understanding and validating user behavior. In addition, Spotify is invested in contributing to academic research by releasing open test collections via competitions such as the RecSys Challenge and the WSDM Cup.