A group of studies have shown that in less developed countries, Purchasing Power Parity (PPP) theory is supported more often when black market exchange rates rather than official rates are used in the testing procedure. They have all relied upon linear Augmented Dickey-Fuller (ADF) test applied...

This article applies standard unit root tests to the spot and forward exchange rates of four core members of the European Monetary System participating in the Exchange Rate Mechanism (ERM). In contrast to the findings of most previous studies, the results show strong evidence of stationarity for...