The IMF Working Papers series is designed to make IMF staff research available to a wide audience. Almost 300 Working Papers are released each year, covering a wide range of theoretical and analytical topics, including balance of payments, monetary and fiscal issues, global liquidity, and national and international economic developments.
Univariate studies of the hypothesis of unit roots in real exchange rates have yielded consensus point estimates of the half-life of deviations from purchasing power parity of between three to five years. However, least squares-based estimates of half-lives are biased downward. Accordingly, we follow Andrews (1993) and use median-unbiased estimators of the half-life of deviations from parity as a preferred measure of the persistence of real exchange rate shocks. We study this issue using real effective exchange rate (REER) data for 22 industrial countries in the post-Bretton Woods period. Three methods of bias correction are implemented, which yield cross-country averages of half-lives of deviations from parity ranging between 4 to 15 years, with the REER of several countries displaying permanent deviations from parity.