Lars Peter Hansen is an American econometrician at the University of Chicago who shared the 2013 Nobel Memorial Prize in Economic Sciences with Eugene Fama and Robert Shiller for their empirical analysis of asset prices. Hansen developed the Generalized Method of Moments (GMM) — a highly flexible and powerful statistical estimation technique that allows economists to estimate structural economic models without fully specifying the underlying probability distribution of the data. GMM has become one of the most widely used tools in macroeconometrics and financial econometrics, enabling researchers to test asset pricing models, estimate dynamic stochastic general equilibrium models, and analyze consumption-based models of the business cycle. Hansen has also made foundational contributions to the study of model uncertainty and robustness in macroeconomic policy, developing tools that allow policy analysis when the precise model of the economy is unknown. His work bridges mathematical statistics, economic theory, and empirical methods in a way that has profoundly influenced quantitative economics.