Foreign exchange markets and the purchasing power parity theory: Evidence from two Southern African countries

The purpose of this paper is to examine the validity of the purchasing power parity (PPP) hypothesis for two Southern African countries, namely: Lesotho and Zambia.

The authors utilized four econometric tests to examine the existence of the PPP hypothesis in Lesotho and Zambia. These tests include two unit root tests without structural breaks – the Dickey-Fuller generalized least squares (DF-GLS) test and the Ng-Perron test; and two unit root tests with structural breaks – the Perron test and the Zivot-Andrews test. The authors’ empirical analysis is based on an annual data set with varying time periods. The sample period spanned 1960-2010 and 1955-2010, for Lesotho and Zambia, respectively.

The authors found that the PPP hypothesis was supported in the case of Lesotho, but rejected in the case of Zambia.

This paper is the first to simultaneously explore the exchange rate policies, trends, and the PPP for these two countries. The implication of this finding is that Lesotho is unlikely to profit immensely from trade and investment arbitrages; whereas Zambia is more likely to profit immensely from trade and investment arbitrage by trading with the USA. Moreover, the authors’ findings indicate that the PPP doctrine may be a useful guide for the exchange rate and other macroeconomic adjustment policies in Lesotho but not in Zambia.