He primarily researches search evaluation, including everything from designing search experiments to building test collections to obtaining relevance judgments to using them in evaluation measures to statistical testing of results. He completed his PhD with James Allan at the University of Massachusetts Amherst on low-cost methods for acquiring relevance judgments for IR evaluation. He has published over 80 papers, won 4 Best Paper Awards, and co-organized two ACM SIGIR-sponsored conferences—WSDM 2014 and ICTIR 2016—in addition to nearly a decade's worth of TREC tracks and several workshops on topics related to new test collections and evaluation. He was also elected SIGIR Treasurer in 2016.