He is the director of the Algorithmic Data Analysis (ADA) programme in HIIT and he leads the Data Mining group in Aalto University. Previously he has been a senior research scientist in Yahoo! Research. He received his Ph.D. from the Computer Science department of Stanford University in 2003. He is currently serving as an associate editor in the IEEE Transactions of Knowledge and Data Engineering (TKDE) and the ACM Transactions of Knowledge Discovery from Data (TKDD), and as a managing editor in Internet Mathematics. He has served in the PC of numerous premium conferences, including being the PC chair for WSDM 2013 and ECML PKDD 2010. He has published over 100 papers and his Google scholar h-index is 40.