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Real exchange rate forecasting: a calibrated half-life PPP model can beat the random walk



This paper brings two new insights into the Purchasing Power Parity (PPP) debate. First, even if PPP is thought to hold only in the long run, we show that a half-life PPP model outperforms the random walk in real exchange rate forecasting, also at short-term horizons. Second, we show that this result holds as long as the speed of adjustment to the sample mean is imposed and not estimated. The reason is that the estimation error of the pace of convergence distorts the results in favor of the random walk model, even if the PPP holds in the long-run.

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  • Michele Ca’ Zorzi & Michal Rubaszek, 2012. "Real exchange rate forecasting: a calibrated half-life PPP model can beat the random walk," NBP Working Papers 123, Narodowy Bank Polski, Economic Research Department.
  • Handle: RePEc:nbp:nbpmis:123

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    References listed on IDEAS

    1. Rossi, Barbara, 2006. "Are Exchange Rates Really Random Walks? Some Evidence Robust To Parameter Instability," Macroeconomic Dynamics, Cambridge University Press, vol. 10(01), pages 20-38, February.
    2. Diebold, Francis X & Mariano, Roberto S, 2002. "Comparing Predictive Accuracy," Journal of Business & Economic Statistics, American Statistical Association, vol. 20(1), pages 134-144, January.
    3. Mark, Nelson C. & Choi, Doo-Yull, 1997. "Real exchange-rate prediction over long horizons," Journal of International Economics, Elsevier, vol. 43(1-2), pages 29-60, August.
    4. Alan M. Taylor & Mark P. Taylor, 2004. "The Purchasing Power Parity Debate," Journal of Economic Perspectives, American Economic Association, vol. 18(4), pages 135-158, Fall.
    5. Mark, Nelson C. & Sul, Donggyu, 2001. "Nominal exchange rates and monetary fundamentals: Evidence from a small post-Bretton woods panel," Journal of International Economics, Elsevier, vol. 53(1), pages 29-52, February.
    6. Murray, Christian J. & Papell, David H., 2002. "The purchasing power parity persistence paradigm," Journal of International Economics, Elsevier, vol. 56(1), pages 1-19, January.
    7. John C. Robertson & Ellis W. Tallman, 1999. "Vector autoregressions: forecasting and reality," Economic Review, Federal Reserve Bank of Atlanta, issue Q1, pages 4-18.
    8. Norman, Stephen, 2010. "How well does nonlinear mean reversion solve the PPP puzzle?," Journal of International Money and Finance, Elsevier, vol. 29(5), pages 919-937, September.
    9. López-Suárez, Carlos Felipe & Rodríguez-López, José Antonio, 2011. "Nonlinear exchange rate predictability," Journal of International Money and Finance, Elsevier, vol. 30(5), pages 877-895, September.
    10. Faust, Jon & Rogers, John H. & H. Wright, Jonathan, 2003. "Exchange rate forecasting: the errors we've really made," Journal of International Economics, Elsevier, vol. 60(1), pages 35-59, May.
    11. Chinn, Menzie D. & Meese, Richard A., 1995. "Banking on currency forecasts: How predictable is change in money?," Journal of International Economics, Elsevier, vol. 38(1-2), pages 161-178, February.
    12. Efthymios G. Pavlidis & Ivan Paya & David A. Peel, 2012. "Forecast Evaluation of Nonlinear Models: The Case of Long‐Span Real Exchange Rates," Journal of Forecasting, John Wiley & Sons, Ltd., vol. 31(7), pages 580-595, November.
    13. Mark, Nelson C, 1995. "Exchange Rates and Fundamentals: Evidence on Long-Horizon Predictability," American Economic Review, American Economic Association, vol. 85(1), pages 201-218, March.
    14. Lutz Kilian & Tao Zha, 2002. "Quantifying the uncertainty about the half-life of deviations from PPP," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 17(2), pages 107-125.
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    Cited by:

    1. Michele Ca'Zorzi & Alexander Chudik, 2013. "Spatial considerations on the PPP debate," Globalization and Monetary Policy Institute Working Paper 138, Federal Reserve Bank of Dallas.

    More about this item


    Exchange rate forecasting; purchasing power parity; half-life;

    JEL classification:

    • C32 - Mathematical and Quantitative Methods - - Multiple or Simultaneous Equation Models; Multiple Variables - - - Time-Series Models; Dynamic Quantile Regressions; Dynamic Treatment Effect Models; Diffusion Processes; State Space Models
    • F31 - International Economics - - International Finance - - - Foreign Exchange
    • F37 - International Economics - - International Finance - - - International Finance Forecasting and Simulation: Models and Applications

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