Fractional cointegration, low frequency dynamics and long-run purchasing power parity: an analysis of the Australian dollar over its recent float

A relatively new but generalized concept of fractional cointegration is applied to shed some light on the validity of purchasing power parity (PPP) as a long-run equilibrium condition, by examining the long-run relationship between quarterly consumer price indices and bilateral exchange rates of the Australian dollar and seven major OECD trading partners, over Australia's recent float. The paper demonstrates that relaxing the condition that the residual from the cointegration equation must be a I(0) process, provides a wide range of cases of parity-reversion with processes that are CI(1,d) with 0 < d < 1. Findings tend to suggest that, while standard tests of cointegration fail to support cointegration between nominal exchange rates, domestic and foreign prices, and thus the empirical favour for PPP as a long-run phenomenon, the fractional cointegration analysis permits deviations from equilibrium to follow a fractionally integrated process and hence captures a much wider class of parity or mean-reversion behaviour. Results are mainly supportive of long-run PPP. Furthermore, an analysis of the short-run dynamics propelling the long-run relationship (through a VECM) reveals that domestic prices are consistently the initial receptor of an exogenous shock to the equilibrium and the long-run equilibrium is restored through the short-run adjustment of the nominal exchange rates. These findings are shown to hold clear policy implications.