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Accuracy, Speed and Robustness of Policy Function Iteration

Author

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  • Todd B. Walker
  • Alexander W. Richter
  • Nathaniel A. Throckmorton

Abstract

Policy function iteration methods for solving and analyzing dynamic stochastic general equilibrium models are powerful from a theoretical and computational perspective. Despite obvious theoretical appeal, significant startup costs and a reliance on grid-based methods have limited the use of policy function iteration as a solution algorithm. We reduce these costs by providing a user-friendly suite of MATLAB functions that introduce multi-core processing and Fortran via MATLAB's executable function. Within the class of policy function iteration methods, we advocate using time iteration with linear interpolation. We examine a canonical real business cycle model and a new Keynesian model that features regime switching in policy parameters, Epstein-Zin preferences, and monetary policy that occasionally hits the zero-lower bound on the nominal interest rate to highlight the attractiveness of our methodology. We compare our advocated approach to other familiar iteration and approximation methods, highlighting the tradeoffs between accuracy, speed and robustness.

Suggested Citation

  • Todd B. Walker & Alexander W. Richter & Nathaniel A. Throckmorton, 2014. "Accuracy, Speed and Robustness of Policy Function Iteration," Auburn Economics Working Paper Series auwp2014-08, Department of Economics, Auburn University.
  • Handle: RePEc:abn:wpaper:auwp2014-08
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    More about this item

    Keywords

    Policy function iteration; Zero lower bound; Epstein-Zin preferences; Markov switching; Chebyshev polynomials; Real business cycle model; New Keynesian model;
    All these keywords.

    JEL classification:

    • C63 - Mathematical and Quantitative Methods - - Mathematical Methods; Programming Models; Mathematical and Simulation Modeling - - - Computational Techniques
    • C68 - Mathematical and Quantitative Methods - - Mathematical Methods; Programming Models; Mathematical and Simulation Modeling - - - Computable General Equilibrium Models
    • E52 - Macroeconomics and Monetary Economics - - Monetary Policy, Central Banking, and the Supply of Money and Credit - - - Monetary Policy
    • E62 - Macroeconomics and Monetary Economics - - Macroeconomic Policy, Macroeconomic Aspects of Public Finance, and General Outlook - - - Fiscal Policy

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