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Imperfect Knowledge and the Pitfalls of Optimal Control Monetary Policy

In: Monetary Policy under Uncertainty and Learning

  • Athanasios Orphanides

    (Central Bank of Cyprus)

  • John C. Williams

    (Federal Reserve Bank of San Francisco)

This paper examines the robustness characteristics of optimal control policies derived under the assumption of rational expectations to alternative models of expectations formation and uncertainty about the natural rates of interest and unemployment. We assume that agents have imperfect knowledge about the precise structure of the economy and form expectations using a forecasting model that they continuously update based on incoming data. We also allow for central bank uncertainty regarding the natural rates of interest and unemployment. We find that the optimal control policy derived under the assumption of perfect knowledge about the structure of the economy can perform poorly when knowledge is imperfect. These problems are exacerbated by natural rate uncertainty, even when the central bank's estimates of natural rates are efficient. We show that the optimal control approach can be made more robust to the presence of imperfect knowledge by deemphasizing the stabilization of real economic activity and interest rates relative to inflation in the central bank loss function. That is, robustness to the presence of imperfect knowledge about the economy provides an incentive to employ a "conservative" central banker. We then examine two types of simple monetary policy rules from the literature that have been found to be robust to model misspecification in other contexts. We find that these policies are robust to the alternative models of learning that we study and natural rate uncertainty and outperform the optimal control policy and generally perform as well as the robust optimal control policy that places less weight on stabilizing economic activity and interest rates.

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This chapter was published in: Klaus Schmidt-Hebbel & Carl E. Walsh & Norman Loayza (Series Editor) & Klaus Schmidt-Hebbel (Series Editor) (ed.) Monetary Policy under Uncertainty and Learning, , chapter 4, pages 115-144, 2009.
This item is provided by Central Bank of Chile in its series Central Banking, Analysis, and Economic Policies Book Series with number v13c04pp115-144.
Handle: RePEc:chb:bcchsb:v13c04pp115-144
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  1. William A. Brock & Steven N. Durlauf & Kenneth D. West, 2005. "Model uncertainty and policy evaluation: some theory and empirics," Proceedings, Federal Reserve Bank of San Francisco.
  2. Levin, Andrew T. & Williams, John C., 2003. "Robust monetary policy with competing reference models," Journal of Monetary Economics, Elsevier, vol. 50(5), pages 945-975, July.
  3. Athanasios Orphanides & John C. Williams, 2003. "Imperfect Knowledge, Inflation Expectations, and Monetary Policy," NBER Working Papers 9884, National Bureau of Economic Research, Inc.
  4. Svensson, Lars E. O. & Williams, Noah, 2005. "Monetary policy with model uncertainty: distribution forecast targeting," Discussion Paper Series 1: Economic Studies 2005,35, Deutsche Bundesbank, Research Centre.
  5. Orphanides, Athanasios & Porter, Richard D. & Reifschneider, David & Tetlow, Robert & Finan, Frederico, 2000. "Errors in the measurement of the output gap and the design of monetary policy," Journal of Economics and Business, Elsevier, vol. 52(1-2), pages 117-141.
  6. Athanasios Orphanides & John C. Williams, 2006. "Inflation Targeting Under Imperfect Knowledge," Working Papers Central Bank of Chile 398, Central Bank of Chile.
  7. Thomas Laubach & John C. Williams, 2001. "Measuring the natural rate of interest," Finance and Economics Discussion Series 2001-56, Board of Governors of the Federal Reserve System (U.S.).
  8. Thomas Laubach, 2001. "Measuring The NAIRU: Evidence From Seven Economies," The Review of Economics and Statistics, MIT Press, vol. 83(2), pages 218-231, May.
  9. Fabio Milani, 2005. "Expectations, Learning and Macroeconomic Persistence," Working Papers 050608, University of California-Irvine, Department of Economics.
  10. Lars E.O. Svensson & Michael Woodford, 2000. "Indicator Variables for Optimal Policy," NBER Working Papers 7953, National Bureau of Economic Research, Inc.
  11. Ann-Charlotte Eliasson & Peter Isard & Douglas Laxton, 1999. "Simple Monetary Policy Rules Under Model Uncertainty," IMF Working Papers 99/75, International Monetary Fund.
  12. Alex Cukierman & Francesco Lippi, 2004. "Endogenous monetary policy with unobserved potential output," Temi di discussione (Economic working papers) 493, Bank of Italy, Economic Research and International Relations Area.
  13. Lars E. O. Svensson & Robert J. Tetlow, 2005. "Optimal policy projections," Finance and Economics Discussion Series 2005-34, Board of Governors of the Federal Reserve System (U.S.).
  14. Athanasios Orphanides & John C. Williams, 2003. "Robust monetary policy rules with unknown natural rates," Finance and Economics Discussion Series 2003-11, Board of Governors of the Federal Reserve System (U.S.).
  15. Athanasios Orphanides & Simon van Norden, 2001. "The Unreliability of Output Gap Estimates in Real Time," CIRANO Working Papers 2001s-57, CIRANO.
  16. Clark, Todd E. & Kozicki, Sharon, 2004. "Estimating equilibrium real interest rates in real-time," Discussion Paper Series 1: Economic Studies 2004,32, Deutsche Bundesbank, Research Centre.
  17. Gaspar, Vítor & Smets, Frank & Vestin, David, 2006. "Adaptive learning, persistence, and optimal monetary policy," Working Paper Series 0644, European Central Bank.
  18. John C. Williams, 1999. "Simple rules for monetary policy," Finance and Economics Discussion Series 1999-12, Board of Governors of the Federal Reserve System (U.S.).
  19. Taylor, John B., 1999. "The robustness and efficiency of monetary policy rules as guidelines for interest rate setting by the European central bank," Journal of Monetary Economics, Elsevier, vol. 43(3), pages 655-679, June.
  20. Andrew T. Levin & Volker W. Wieland & John C. Williams, 1998. "Robustness of simple monetary policy rules under model uncertainty," Finance and Economics Discussion Series 1998-45, Board of Governors of the Federal Reserve System (U.S.).
  21. Milton Friedman, 1947. "Lerner on the Economics of Control," Journal of Political Economy, University of Chicago Press, vol. 55, pages 405.
  22. Kenneth Rogoff, 1985. "The Optimal Degree of Commitment to an Intermediate Monetary Target," The Quarterly Journal of Economics, Oxford University Press, vol. 100(4), pages 1169-1189.
  23. Mccallum, Bennet T., 1988. "Robustness properties of a rule for monetary policy," Carnegie-Rochester Conference Series on Public Policy, Elsevier, vol. 29(1), pages 173-203, January.
  24. Thomas J. Sargent, 2008. "Evolution and Intelligent Design," American Economic Review, American Economic Association, vol. 98(1), pages 5-37, March.
  25. Marc P. Giannoni & Michael Woodford, 2003. "Optimal Inflation Targeting Rules," NBER Working Papers 9939, National Bureau of Economic Research, Inc.
  26. Marcet, Albert & Sargent, Thomas J., 1989. "Convergence of least squares learning mechanisms in self-referential linear stochastic models," Journal of Economic Theory, Elsevier, vol. 48(2), pages 337-368, August.
  27. Robert J. Tetlow, 2010. "Real-time model uncertainty in the United States: 'Robust' policies put to the test," Finance and Economics Discussion Series 2010-15, Board of Governors of the Federal Reserve System (U.S.).
  28. Wiliam Branch & George W. Evans, 2005. "A Simple Recursive Forecasting Model," University of Oregon Economics Department Working Papers 2005-3, University of Oregon Economics Department, revised 01 Feb 2005.
  29. Andrew Levin & John C. Williams, 2000. "The Performance of Forecast-Based Monetary Policy Rules under Model Uncertainty," Econometric Society World Congress 2000 Contributed Papers 1781, Econometric Society.
  30. Schmidt-Hebbel, Klaus & Tapia, Matias, 2002. "Inflation targeting in Chile," The North American Journal of Economics and Finance, Elsevier, vol. 13(2), pages 125-146, August.
  31. Timothy Cogley & Thomas Sargent, . "Evolving Post-World War II U.S. Inflation Dynamics," Working Papers 2132872, Department of Economics, W. P. Carey School of Business, Arizona State University.
  32. Taylor, John B., 1993. "Discretion versus policy rules in practice," Carnegie-Rochester Conference Series on Public Policy, Elsevier, vol. 39(1), pages 195-214, December.
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