His methodological research centers on learning more from social policy evaluations, especially randomized experiments. His applied research focuses on working with governments to use data to design and implement policy interventions, including through Pay for Success contracts and Social Impact Bonds. Prior to his doctoral studies, Feller served as Special Assistant to the Director at the White House Office of Management and Budget and worked at the Center on Budget and Policy Priorities. Feller received a Ph.D. in Statistics from Harvard University, an M.Sc. in Applied Statistics as a Rhodes Scholar at the University of Oxford, and a B.A. in Political Science and Applied Mathematics from Yale University.