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Accuracy, Speed and Robustness of Policy Function Iteration

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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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    File URL: http://cla.auburn.edu/econwp/Archives/2014/2014-08.pdf
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    Cited by:

    1. Richter Alexander W. & Throckmorton Nathaniel A., 2015. "The zero lower bound: frequency, duration, and numerical convergence," The B.E. Journal of Macroeconomics, De Gruyter, vol. 15(1), pages 1-26, January.
    2. William T. Gavin & Benjamin D. Keen & Alexander W. Richter & Nathaniel A. Throckmorton, 2013. "Global Dynamics at the Zero Lower Bound," Auburn Economics Working Paper Series auwp2013-17, Department of Economics, Auburn University.
    3. Gavin, William T. & Keen, Benjamin D. & Richter, Alexander W. & Throckmorton, Nathaniel A., 2015. "The zero lower bound, the dual mandate, and unconventional dynamics," Journal of Economic Dynamics and Control, Elsevier, vol. 55(C), pages 14-38.
    4. Leith, Campbell & Liu, Ding, 2016. "The inflation bias under Calvo and Rotemberg pricing," Journal of Economic Dynamics and Control, Elsevier, vol. 73(C), pages 283-297.
    5. Abo-Zaid, Salem, 2015. "Optimal long-run inflation with occasionally binding financial constraints," European Economic Review, Elsevier, vol. 75(C), pages 18-42.
    6. Richter, Alexander W. & Throckmorton, Nathaniel A., 2015. "The consequences of an unknown debt target," European Economic Review, Elsevier, vol. 78(C), pages 76-96.
    7. Shen, Wenyi, 2015. "News, disaster risk, and time-varying uncertainty," Journal of Economic Dynamics and Control, Elsevier, vol. 51(C), pages 459-479.
    8. repec:bla:ecinqu:v:55:y:2017:i:4:p:1593-1624 is not listed on IDEAS
    9. Michael Plante & Alexander W. Richter & Nathaniel A. Throckmorton, 2018. "The Zero Lower Bound and Endogenous Uncertainty," Economic Journal, Royal Economic Society, vol. 128(611), pages 1730-1757, June.
    10. Junior Maih, 2014. "Efficient Perturbation Methods for Solving Regime-Switching DSGE Models," Working Papers No 10/2014, Centre for Applied Macro- and Petroleum economics (CAMP), BI Norwegian Business School.
    11. Benjamin D. Keen & Alexander W. Richter & Nathaniel A. Throckmorton, 2017. "Forward Guidance And The State Of The Economy," Economic Inquiry, Western Economic Association International, vol. 55(4), pages 1593-1624, October.
    12. Takefumi Yamazaki, 2018. "Financial friction sources in emerging economies: Structural estimation of sovereign default models," Discussion papers ron303, Policy Research Institute, Ministry of Finance Japan.
    13. Hirokuni Iiboshi & Mototsugu Shintani & Kozo Ueda, 2018. "Estimating a Nonlinear New Keynesian Model with a Zero Lower Bound for Japan," Working Papers e120, Tokyo Center for Economic Research.
    14. Richter, Alexander W. & Throckmorton, Nathaniel, 2017. "A New Way to Quantify the Effect of Uncertainty," Working Papers 1705, Federal Reserve Bank of Dallas, revised 23 Feb 2018.
    15. Romain Ranciere & Nathaniel A. Throckmorton & Michael Kumhof & Claire Lebarz & Alexander W. Richter, 2012. "Income Inequality and Current Account Imbalances," IMF Working Papers 12/8, International Monetary Fund.
    16. Richter, Alexander W., 2015. "Finite lifetimes, long-term debt and the fiscal limit," Journal of Economic Dynamics and Control, Elsevier, vol. 51(C), pages 180-203.
    17. repec:mof:journl:ppr14_04_06 is not listed on IDEAS

    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;

    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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