Non-linear quantile unit root test and PPP: more evidence from Africa

It is now a common practice to establish stationarity of the real exchange rate as a sign of purchasing power parity (PPP) hypothesis. In this article, we consider the real effective exchange rates of 29 African countries. When we apply conventional linear unit root tests, we find support for the PPP in eight countries. However, when we shift to the newly introduced non-linear quantile unit root test, support for the PPP increases to 15 countries.     

Fourier nonlinear quantile unit root test and PPP in Africa

We test the PPP hypothesis in 29 African countries using a newly developed nonlinear Quantile unit root test with a Fourier function which accounts for smooth breaks. Simulation indicates that the proposed new test has higher power than the conventional Quantile unit root test as proposed by Koneker and Xiao (2004). Our empirical results provide support for the PPP hypothesis in 21 out of 29 African countries, a unique discovery using their real effective exchange rates. It appears that incorporating Fourier function to nonlinear Quantile unit root test gets us closer and closer to solving the PPP puzzle in Africa.     

Revisiting Purchasing Power Parity in OECD

This study revisits Purchasing Power Parity theory (PPP) in the 34 OECD countries during January 1994–August 2013. We use a new panel stationary test with both sharp breaks and smooth shifts, a novel approach to panel unit-root testing, proposed by Bahmani–Oskooee et al. (2014). The results indicate that the PPP holds in half of the 34 OECD countries. These results indicate the importance of proper modelling of both sharp breaks and smooth shifts in real effective exchange rate series of OECD countries.     

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.     

Unemployment persistence in EU countries: new evidence using bounded unit root tests

We apply a series of bounded unit root tests to revisit the unemployment persistence in eight European Union (EU) countries. We find strong evidence in favour of the hysteresis hypothesis in all the cases. This result can be explained by a reduced labour mobility, a decreasing wage inflation and a high uncertainty regarding the future level of unemployment in the EU countries.     

Unit root and trend breaks in per capita output: evidence from sub-Saharan African countries

This article examines the nonstationary properties of per capita real output in 28 sub-Saharan African (SSA) countries, covering the period 1960–2014. The sequential testing approach proposed by Kejriwal and Lopez (2013, Econometric Reviews 32(8), 892–927) is used to categorize SSA countries into growth shift, level shift and linear trend hypotheses based on the presence or not of breaks in slope and/or level of the trend function. The break dates are associated to major historical or economic events such as sociopolitical crisis, commodity price fluctuations on international market, the discovery and the exploitation of mineral deposits or unfavourable environmental and climatic conditions. The empirical evidences of appropriate unit root tests fail to reject the unit root hypothesis in all the countries, suggesting that a shock would have a permanent effect on growth process, and stabilization policies may be implemented in dealing with income fluctuations.     

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).     

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.     

Panel LM unit root tests with level and trend shifts

This paper considers a Lagrange multiplier (LM) based panel unit root test that allows for heterogeneous structural breaks in both the intercepts and slopes of a series. We note that many popular time series variables are likely to exhibit changing means and/or trends over time. Given that the usual tests will depend on the nuisance parameters indicating the locations of the trend breaks, we adopt a transformation procedure that makes our new panel unit root tests invariant to the nuisance parameters. To illustrate the importance of the power gain provided by our test, we examine the convergence hypothesis using relative ratios of per capita health care expenditures in 20 OECD countries. Our results provide evidence that the convergence hypothesis is supported.     

Stochastic convergence of per capita carbon dioxide emissions and multiple structural breaks in OECD countries

This research applies an innovative panel data stationarity testing procedure developed by Carrion-i-Silvestre et al. [Carrion-i-Silvestre, J.L., Barrio-Castro, T.D. and Lopez-Bazo, E., 2005. Breaking the panels: An application to the GDP per capita, Econometrics Journal 8, 159–175.], which has the advantage of recognizing multiple structural breaks and the presence of cross-section dependence in order to re-investigate the hypothesis that per capita carbon dioxide (CO₂) emissions stochastically converge for 21 OECD countries from 1950 to 2002. Remarkably, the evidence clearly indicates that the panel dataset of relative per capita CO₂ emissions is stationary after the structural breaks and cross-sectional dependence are introduced into the model. These findings offer strong policy implications for governments, regardless of whether they are in “convergent group” or “divergent group” countries. We also find that the structural breaks in the 1960s and over the 1970–1982 period are associated with time periods of fossil fuel becoming the main source of productivity, higher oil prices, and the development of nuclear power.     

Testing hysteresis effect in U.S. state unemployment: new evidence using a nonlinear quantile unit root test

We revisit hysteresis effect in the unemployment rate of each of the 52 states of the United States using nonlinear quantile unit root test over the period 1976M1–2016M7. Our results indicate that unemployment rate of the U.S. economy as a whole displays hysteresis effect over recessionary periods. Nineteen out of 52 states display hysteresis behaviour over the period 1976–2016. For the remaining 33 states, we find four types of behaviours. Some states display stationarity behaviour almost in all quantiles. Some display hysteresis over recessionary periods and in contrast some display hysteresis over expansion period.     

Foreign investments in real estate,economic growth and property prices: evidence from OECD countries

The last two decades have witnessed a growth in foreign direct investments (FDI) in the real estate sector in most of the Organization for Economic Co-Operation and Development (OECD) countries. It is argued that FDI in the real estate sector may improve economic growth in recipient economies. On the other hand, property prices have increased considerably in OECD countries in recent years and some argue that FDI in real estate is one of the driving forces of high property prices in these countries. The purpose of this study is to analyze the interrelationship between FDI in the real estate sector, economic growth, and property prices while controlling for interest rate and inflation. We use observations from a set of OECD countries for the period between 1995 and 2008. The dynamic interrelationship is analyzed by applying a panel cointegration technique. Our empirical results show that FDI in real estate do not cause property price appreciations and also do not contribute to economic growth in OECD countries in the short run and the long run.     

Long-run estimates of money demand: new evidence from East Asian countries and the presence of structural breaks

Conventionally, the money demand function is estimated using a linear regression of the logarithm of money demand on a number of variables. In this article, we aim to estimate the long-run properties of money demand specification for a number of East Asian economies and within a panel framework with the presence of structural breaks. Various country-specific coefficients are allowed to capture inter-country heterogeneities. Consistent with theoretical postulates, it is found that (a) the demand for money in the long-run positively responds to real income and inversely to the interest rate spread, inflation, the real effective exchange rate and the US real interest rate; (b) the long-run income elasticity is greater than unity; and (c) both the currency substitution and capital mobility hypotheses hold. The empirical findings in this article can provide useful policy guidelines to the East Asian countries’ central banks in their quest for price stability. If one of the primary objectives of these countries is to minimize price instability, they should avoid creating unnecessary disequilibrium in the money market, while the employment of cointegration with the presence of structural breaks clearly recommends to central banks to use the supply of money to attain price and macroeconomic stability.     

Quantile nonlinear unit root test with covariates and an application to the PPP hypothesis

In this article, we employ the methods initiated by Hansen (1995) to develop new quantile nonlinear unit root tests with covariates. The limiting distributions of our proposed tests are derived, which are dependent on nuisance parameter reflecting the correlation between the equation error and the covariates. To deal with this inferential difficulty, two alternative procedures based on either consistent estimate of the nuisance parameter or bootstrap implementation of the test are proposed. Monte Carlo simulations show that the proposed tests perform very well in finite samples and large power gains can be achieved by including correlated covariates in the testing equation. The proposed tests are applied to the PPP hypothesis. The empirical results indicate that the real exchange rates are not constant unit root processes.     

Stochastic convergence in per capita energy consumption and its catch-up rate: evidence from 26 African countries

Using annual data from 1971 to 2014, we examine stochastic conditional convergence in per capita energy consumption for 26 low income, lower middle-income and upper-middle-income African countries. To do so, we use panel unit root tests that allow for cross-sectional dependence and structural breaks as well as the recently developed univariate Residual Augmented Least Squares-Lagrange multiplier (RALS-LM) unit root test with structural breaks. Although for most countries our evidence suggests stochastic conditional convergence, we find divergence for four countries including DR Congo, Senegal, Egypt and Botswana. Consistent with the neoclassical growth models we also examine the catch-up rate between energy consumption levels of African economies and that one of China and investigate its convergence properties. As African economies continue to grow, regional energy consumption disparity narrows, African energy consumption levels will catch up to the ones in China.     

Testing for weak-form efficiency of crude palm oil spot and future markets: new evidence from a GARCH unit root test with multiple structural breaks

There is a sizeable literature that tests for weak-form efficiency in commodity and energy spot and future prices. While many studies now allow for multiple structural breaks to address the criticism that conventional unit root tests have low power to reject the unit root null in the presence of structural change, the extant literature overlooks the fact that conventional unit root tests are biased in the presence of conditional heteroscedasticity. We apply a recently developed generalized autoregressive conditional heteroscedasticity (GARCH) unit root test with multiple structural breaks to crude palm oil spot and future prices and find much more evidence against weak-form efficiency than that found using tests that fail to allow for conditional heteroscedasticity. Our results point to the importance of allowing for heteroscedasticity when testing for efficiency in commodity and energy spot and future prices.     

Nonlinearity and stationarity of inflation rates: evidence from the euro-zone countries

Earlier studies hardly reject the hypothesis of a unit root in inflation. Few studies have examined the possibility of nonlinearity in inflation and tested nonlinear stationarity of the inflation rates. This study thus intends to fill the gap. This study utilizes the tests for nonlinearity along with the unit root tests that allow for nonlinearity in the variables to examine the stationarity of inflation rates of 12 European countries that formed the Euro Zone (EZ) later in the sample period. The results suggest that the majority of these countries’ inflation rates can be characterized by mean reversion during the floating exchange rate period. Many of them appear to be nonlinear stationary. This finding is essential in conducting applied economic studies for these countries, when constructing models whose validity relies on whether or not inflation is stationary. The results of this study also imply that shocks to inflation have a transitory effect on inflation in the euro area. Therefore, it would be less costly in exercising the policies of disinflation for the monetary authorities of the euro area than for those of the countries with nonstationary inflation.     

An empirical research of crude oil price changes and stock market in China: evidence from the structural breaks and quantile regression

This article investigates the relationship between real crude oil price changes and the Chinese real stock market at the industry level. Our study uses monthly data over the period 1994:03 to 2013:12. Based on input–output (IO) tables, this article will explore more details for the driving factors of sensitivity to oil price changes. We divide these driving factors into cost- and demand-side dependence. Empirical results reveal that sensitivity varies across different industries and periods based on structural breaks and asymmetric effects of oil price changes. Furthermore, some industries seemingly not directly affected by oil are sensitive to the real oil price changes. Finally, using a penalized quantile regression for panel data, we find that these two factors significantly affect lower, but not upper, quantile of sensitivity.     

Revisiting the uncertain unit root in GDP and CPI: Testing for non-linear trend reversion

We test for the presence of a unit root in U.S. GDP and CPI, allowing for non-linear trend reversion under the alternative hypothesis. In contrast to most previous results, we find evidence in favour of trend stationarity for both variables.