Stern School of Business of New York University. His recent research interests focus on crowdsourcing. He received his PhD in computer science from Columbia University in 2004, with distinction, and has received two Microsoft Live Labs Awards, two best paper awards (IEEE ICDE 2005, ACM SIGMOD 2006], two runner up awards for best paper [JCDL 2002, ACM KDD 2008], and a CAREER award from the National Science Foundation. This work was supported by the National Science Foundation under Grant No. IIS0643846.