Purchasing power parity (PPP) between South Africa and her main currency exchange partners: Evidence from asymmetric unit root tests and threshold co-integration analysis

Purpose: This purpose of this study is to examine the asymmetric adjustment effects for the purchasing power parity (PPP) for South Africa against her main currency trading partners; namely, the US, the UK, the Euro area, China and Japan. Design/Methodology/Approach: This study presents a two-fold empirical approach by using nominal exchange rate and aggregate price level data collected monthly for the periods 1971-2013. As a first step, the paper tests for nonlinear integration properties on the real exchange rate as computed as the nominal exchange rate adjusted for price differentials between the domestic and foreign price levels. The paper then proceeds to investigate asymmetric cointegration and error correction effects between nominal exchange rates and aggregate price differentials; and further supplements the empirical analysis by investigating granger causal effects between the variables. Findings: While the study is able to validate significant asymmetric PPP effects between South Africa and all her main currency exchange partners through the application of asymmetric unit root tests; the evidence presented when examining these PPP effects through the use of threshold cointegration and error correction analysis exempts the relationship explored between South African and the Euro area. Furthermore, the causal effects are found to run uni-directional from exchange rates to aggregate price differentials for all significant asymmetric cointegration relations. Originality/value: This study makes a novel contribution to literature by confirm significant asymmetric PPP effects between South Africa and her main currency exchange partners from both a unit root and a co-integration perspective.