Revisiting purchasing power parity for African countries: with nonlinear panel unit-root tests

This study applies Panel Seemingly Unrelated Regressions (SUR) Kapetanios et al. (Kapetanios–Shin–Snell (KSS), SURKSS) tests, proposed by Wu and Lee (2009), to investigate the properties of long-run Purchasing Power Parity (PPP) in 15 African countries. The empirical results from the univariate unit root and panel based unit root tests indicate that PPP does not hold for these 15 countries under study. However, Panel SURKSS tests indicate that PPP is valid for four of these 15 countries. These results have important policy implications for these 15 African countries under study.     

Testing the purchasing power parity in panel data

This paper empirically tests the purchasing power parity (PPP) using panel unit root tests. We employ a battery of panel unit root tests: LM-bar statistic [Testing for unit roots in heterogeneous panels, Working paper, University of Cambridge] is employed to account for serially correlated errors. The statistic proposed by Breitung [Adv. Econom. 15 (2000) 161.] and the KPSS-based statistic of Hadri [Econ. J. 3 (2000) 148.] are also used. In addition, we also employ a SUR estimator to account for possible cross-sectional effect. Data of 45 economies from 1980 to 1999 are used to test the PPP hypothesis. We find that these estimators tend to get supportive results when the data frequency becomes lower, which substantially characterizes the long-run property of the PPP hypothesis.     

Flexible Fourier stationary test in purchasing power parity for African countries

This study applies stationary test with a Fourier function proposed by Enders and Lee (2004 Enders, W and Lee, J. 2004. Testing for a unit root with a nonlinear Fourier function, Tuscaloosa, AL, , USA: Working Paper, Department of Economics, Finance and Legal Studies, University of Alabama.  [Google Scholar], 2009 Enders, W and Lee, J. 2009. The flexible Fourier form and testing for unit roots: an example of the term structure of interest rates, Tuscaloosa, AL, , USA: Working Paper, Department of Economics, Finance and Legal Studies, University of Alabama.  [Google Scholar]) to test the validity of long run Purchasing Power Parity (PPP) to assess the nonstationary properties of the real exchange rate for 20 African countries. We find that our approximation has higher power to detect U shaped breaks and smooth breaks than linear method if the true data generating process of exchange rate is in fact a stationary nonlinear process. We examine the validity of PPP from the nonlinear point of view and provide robust evidence clearly indicate that PPP holds true for almost African countries. Our findings point out their exchange rate adjustment is mean reversion towards PPP equilibrium values in a nonlinear way.     

The purchasing power parity puzzle is worse than you think

The ‘‘purchasing power parity puzzle’’ is the difficulty of reconciling very high short-term volatility of real exchange rates with very slow rates of mean reversion. The strongest evidence of slow mean reversion comes from least squares estimates of first-order autoregressive models of the long-horizon dollar-sterling real exchange rate. Using median-unbiased estimation methods, we show that these methods underestimate the half-lives of PPP deviations, and thus overestimate the speed of mean reversion. When the specification is amended to allow for serial correlation, the speed of mean reversion falls even further. This makes resolution of the purchasing power parity puzzle more problematic.First version received: May 2003/Final version received: July 2004We thank Lutz Kilian, James Lothian, Mark Taylor, and two anonymous referees for helpful comments and suggestions.     

Testing the relative purchasing power parity hypothesis: the case of Korea

This study examines the relative purchasing power parity (PPP) hypothesis using the data from the Korean won–US dollar and the Korean won–Japanese yen foreign exchange markets. We extract proxies for inflation from stock market returns of Korea, the United States and Japan based on the method used by Chowdhry, Roll and Xia in 2005. We explicitly test the relative PPP hypothesis in light of the short-run price volatility using monthly, bimonthly and quarterly data from 1 January 1998 to 31 December 2012. Our findings suggest that the empirical test results from the entire sample period do not support the relative PPP hypothesis. However, the results from the sample period excluding the Asian Financial Crisis period show that the relative PPP hypothesis holds for the Korean won–US dollar market with a moderate magnitude of inflation impact, but not for the Korean won–Japanese yen market. Abrupt changes in exchange rates during the crisis period may have affected the relationship between inflation and exchange rates. This result also suggests that factors other than inflation might have affected the Korean won–Japanese yen exchange rate.     

Examining the evidence of purchasing power parity by recursive mean adjustment

This paper revisits the empirical evidence of purchasing power parity under the current float by recursive mean adjustment (RMA) proposed by So and Shin (1999). We first report superior power of the RMA-based unit root test in finite samples relative to the conventional augmented Dickey–Fuller (ADF) test via Monte Carlo experiments for 16 linear and nonlinear autoregressive data generating processes. We find that the more powerful RMA-based unit root test rejects the null hypothesis of a unit root for 16 out of 20 current float real exchange rates relative to the US dollar, while the ADF test rejects only 5 at the 10% significance level. We also find that the computationally simple RMA-based asymptotic confidence interval can provide useful information regarding the half-life of the real exchange rate.     

Panel asymmetric nonlinear unit root test and PPP in Africa

This study revisits purchasing power parity (PPP) theory for 20 African countries using panel asymmetric nonlinear unit root test proposed by Emirmahmutoglu and Omay (2014), through the sequential panel selection method of Chortareas and Kapetanios (2009). While standard panel unit root tests fail to support the PPP, the empirical results from panel asymmetric nonlinear unit root test do support the PPP. However, additional tests reveal that support in all 20 African countries is mostly due to stationarity of the real effective exchange rates of Ghana and Rwanda where the adjustment process towards equilibrium is nonlinear and asymmetric.     

Revisiting purchasing power parity for East Asian countries using the rank test for nonlinear cointegration

This study applies a simple and powerful nonlinear rank test, proposed by Breitung (2001) to test the validity of long-run Purchasing Power Parity (PPP) in a sample of East Asian countries over the period March 1985–September 2008. The empirical results indicate that PPP holds for all of East Asian countries studied and the nominal exchange rate, domestic Consumer Price Index (CPI) and the US CPI are all linearly interrelated with the exception of China. Our results have important policy implications for these East Asian countries under study.     

An empirical analysis on the law of purchasing power parity and international economic deepening

This article empirically investigates the effect of international trade on the deviation of Purchasing Power Parity (PPP) law and on the international economic deepening in four developed countries (Japan, USA, UK and France), and three Asian developing ones (South Korea, Singapore and Malaysia), using International Financial Statistics (IFS) data issued by International Monetary Fund (IMF). Our results show that in some developed countries the imbalance effect of balance of payments is significant for both international deepening and deviation from PPP, and in some developing countries the volume effect of balance of payments is significant for international deepening.     

Correlates of economic growth in developing countries: a panel cointegration approach

The inflow of foreign direct investment (FDI) has been found to play a crucial role in the economic growth of receiving countries. Using panel cointegration techniques, this perception was found to be mitigated by an empirical approach that yields different results from previous studies. While the growth in real FDI has an influence on real GDP growth across developing countries in the short-run, year-to-year periods, it does not explain real GDP in the long-run. Rather, it appears to be the economic factors internal to a country that have the most influence on real GDP over time: human capital (measured by literacy rates), export trade, and monetary and fiscal policy.     

Quantile unit root test and the PPP in Africa

In this study, we apply the Quantile unit root test and revisit the Purchasing Power Parity (PPP) in 20 African countries using real effective exchange rates over the period 1971Q1 to 2012Q4. While traditional unit root tests fail to reject unit root hypothesis in most of the countries, results from Quantile unit root test reject unit root null hypothesis in Ghana, Mauritius, Niger, South Africa, and Togo, providing support for the PPP at least in these five countries. We further estimate the half-life based on Quantile autoregressive (QAR) model to be about 4.57–7.96 quarters (1–2 year).     

Real interest rate parity in Asian countries: evidence from the quantile unit root test

This article studies the real interest rate parity (RIP) for several Asian countries. This is done by examining the stationarity in the real interest rate differentials (rids) with respect to the US using the quantile unit root test. Our results show that rids exhibits unit-root behaviours in the lower quantile levels, and mean reversion in the upper quantile levels. Furthermore, large positive shocks tend to induce strong mean reversion and the adjustment towards the long-run equilibrium level is faster as rids gets larger, with shorter half-lives in the extreme quantile levels.     

Testing the validity of PPP theory for African countries

This study examines the purchasing power parity theory for 14 African countries by applying a recent composite time series method that incorporates the Fourier approximation. The structural breaks are modelled as a gradual smooth process by means of a Fourier component. The Fourier unit root test failed to find any evidence showing that real exchange rates for these 14 countries have mean-reverting tendencies. However, both cointegration and Fourier cointegration tests detect a stable long-term relation between the nominal exchange rate and relative price levels for 8 out of 14 countries; moreover, for five countries Fourier component in cointegration analysis is found to suit quite well.     

Purchasing power parity vs. uncovered interest rate parity for NAFTA countries: The value of incorporating time-varying parameter model

In 1994, the United States, Canada, and Mexico signed the North American Free Trade Agreement (NAFTA) to strengthen economic cooperation. To examine the effects of the NAFTA, this study revisits Purchasing Power Parity (PPP) for NAFTA countries by applying a time-varying cointegration model. Under the time-varying assumption, it improves the explanatory power of reality via the model specification test. Given that, the validity of PPP for NAFTA countries varies over time. Especially, the PPP elasticity based on the consumer price index (CPI) is more volatile than the producer price index (PPI) -based. Thus, the stabilization policy of the consumption sector must be a high priority over the production sector. Moreover, the validity of the Uncovered Interest Rate Parity (UIRP) is examined by the time-varying cointegration model. The aim is to compare the results of the PPP and UIRP. This suggests that the PPP is more useful than the UIRP in evaluating the movement of the exchange rate in the long-run.     

Investigation of the nonlinear behaviour in real exchange rates in developing regions

This article examines whether the purchasing power parity (PPP) theory holds or not for the economies in different developing regions located in Africa, Asia and Latin America. In order to investigate this issue, a nonlinear panel unit root test is used to determine if some or all of the real exchange rates in a panel follow a stationary exponential smooth transition autoregressive process. By applying the nonlinear panel unit root test, our results demonstrate an empirical support for the theory of PPP for the economies in developing regions.     

PPP: Further evidence from Japanese regional data

This paper empirically analyzes Purchasing Power Parity (PPP) among Japanese municipalities from 1990 to 2003. Using panel unit root tests including one that considers cross-sectional dependence in the data (e.g., [Moon, H. R. and Perron, B. (2004). Testing for a unit root in panels with dynamic factors. Journal of Econometrics, 112, 81–126.]), we find evidence in favor of PPP, confirming the stationarity of relative prices in Japan and thus the long-run co-movement of municipal prices. Furthermore, the half-life of a shock is found to be about 2 years, which is faster than that of the international PPP. As in the European and US studies, short-term deviations from PPP can be explained by income differentials and distance between cities.     

Purchasing power parity with flexible Fourier stationary test for Central and Eastern European countries

This study applies stationary test with a Fourier function proposed by Enders and Lee (2004, 2009) to test the validity of long-run Purchasing Power Parity (PPP) to assess the nonstationary properties of the Real Exchange Rate (RER) for seven Central and Eastern European Countries (CEECs). We find that our approximation has higher power to detect U-shaped breaks and smooth breaks than linear method if the true data generating process of exchange rate is in fact a stationary nonlinear process. We examine the validity of PPP from the nonlinear point of view and provide robust evidence clearly indicating that the PPP holds true for all CEECs. Our findings point out their exchange rate adjustment is mean reversion towards PPP equilibrium values in a nonlinear way.     

Instability in short-run adjustments to purchasing power parity: results for selected Latin American countries

According to the theory of purchasing power parity (PPP), there is a tendency toward equalization of different countries' price levels in common-currency terms. However, even assuming that a long-run PPP relationship exists, its relevance for policy makers in less developed countries (LDCs) will depend not only on the average speed of adjustment toward this relationship but also on the variability of such short-run adjustments. We present evidence of extreme volatility in adjustments toward PPP for four Latin American countries, based on time-varying-parameter estimates of error-correction models.     

Evidence on the purchasing power parity in a panel of cities

Evidence is provided on the PPP hypothesis using a sample of 50 Spanish cities for a long time period through the application of panel data unit root tests. Although results suggest non-rejection of the PPP, short-run deviations – as measured by half-lives – indicate that real factors might be causing a slow rate of convergence to a common price index, even in highly integrated economies.