A common finding in the empirical literature on the validity of purchasing power parity (PPP) is that it holds when tested for in panel data, but not in univariate (i.e. country-specific) analysis. The usual explanation for this mismatch is that panel tests for unit roots are more powerful than...

We show how the use of panel data methods such as those proposed in single equations by Kao (1999) and Pedroni (1999) or in systems by Larsson and Lyhagen (1999) to investigate economic hypotheses such as purchasing power parity or the term structure of interest rates may be affected by the...