Purchasing Power Parity Between the UK and Germany: The Euro Era

We use the Johansen cointegration approach to assess the empirical validity of the purchasing power parity (PPP) between the UK and Germany since the introduction of the euro. We conduct the empirical analysis in the context of the global financial crisis that began in 2007 and find that it directly affects the cointegration space. We fail to validate the Johansen and Juselius (1992) original hypothesis that nonstationarity of PPP associates with the nonstationarity of interest rate differentials to produce a stationary relation. On the other hand, we do not reject PPP. We find that PPP cointegrates with inflation differentials. We also find, contrary to conventional wisdom, that (i) equilibrium adjustment occurs between the German and UK inflation rates, while weak exogeneity exists for the German and UK interest rates and the PPP condition, and (ii) three common trends associated with the German interest rate the UK interest rate, and the PPP condition “push” the system with the German interest rate and the PPP condition playing dominant roles in affecting inflation in both Germany and the UK. These results cast serious doubt on the presumed independence of the UK monetary policy.