He received his PhD from the University of Pennsylvania in 2004 and joined the faculty at Maryland that year. He is a macroeconomist with both theoretical and empirical interests. On the theoretical front, his recent research focuses on the dynamics of an economy when it is at the zero lower bound of nominal interest rates and in general nonlinearities in macroeconomic models. On the empirical front, he worked on understanding statistical properties of data revisions, the yield curve and factor models. His work on an index for tracking business cycles and a new measure of GDP are implemented by the Federal Reserve Bank of Philadelphia.