Program in Educational Psychology’s Quantitative specialization. He joined the Graduate Center as a faculty member in 2007. His research focuses on generalized linear mixed models, item response theory, graphical methods in statistics, and on applications of statistics and psychometrics, particularly in education and mental health. His work has appeared in numerous journals, including Psychological Methods, the Journal of Mathematical Psychology, Applied Psychological Measurement, the Journal of Educational and Behavioral Statistics, and Psychological Assessment. He was the book review editor of the Journal of Educational and Behavioral Statistics from 2008 to 2012 and is currently an associate editor of Educational Measurement: Issues and Practice.