Econometric models are statistical models used in econometrics. He specializes in the fields of macroeconomics, monetary economics and time series econometrics. He has written extensively in the fields of macroeconomics, econometrics and public policy. The main statistical method in econometrics is multivariable regression analysis. Economics has contributed notably through spatial econometrics. Statistical software are specialized computer programs for analysis in statistics and econometrics. Idempotent matrices arise frequently in regression analysis and econometrics. These quantitative analysts tend to rely more on numerical analysis than statistics and econometrics. It has applications in physics, econometrics, and bioinformatics, among others. Quantile regression is a type of regression analysis used in statistics and econometrics. Mathematical models also include those in game theory, linear programming, and econometrics. A basic tool for econometrics is the multiple linear regression model. It has proved popular in regression analysis, including econometrics. Economic theories are frequently tested empirically, largely through the use of econometrics using economic data. This can be done with simultaneous-equation methods of estimation in econometrics.