Real exchange rates and unit root tests

This paper examines monthly OECD exchange rate data (1979-1997) using univariate and panel data unit root tests. Some of these tests support the hypothesis of a unit root. But tests of cointegration reveal the existence of weak purchasing power parity relationships between bilateral nominal exchange rates and relative prices. We suggest that researchers need not conduct unit root tests on real exchange rate data when a modified version of PPP is used; or if there is a long enough time series. Given the definition of real exchange rates, the indicator should be stationary and should have intrinsic mean reverting behaviour. JEL no. C23, F31.