This paper analyzes the issue of purchasing power parity using real effective exchange rate (REER) data for 20 industrial countries in the post-Bretton Woods period. The serial correlation-robust median-unbiased estimator yields a cross-country average of half-lives of deviations from parity of about eight years, with the REER of several countries displaying permanent deviations from parity. The paper analyzes integration of Africa into world trade...