Before joining CMU, he was a senior research scientist at Max Planck Institute for Intelligent Systems, Germany, and a lead scientist at Information Sciences Institute of University of Southern California. His main research interests include causal analysis, machine learning, artificial intelligence, and computational finance. He has made a series of contributions in solving some long-standing problems in causality, such as how to distinguish cause from effect and how to make nonparametric conditional independence test reliable. He has served as a senior program committee member or area chair for a number of conferences in machine learning or artificial intelligence, and organized various academic activities to foster interdisciplinary research in causality.