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.     

Convergence of international output Time series evidence for 16 OECD countries

This article examines convergence of per capita output for 16 OECD (Organization for Economic Cooperation and Development) countries. Conventional tests on conditional and time series convergence have given mixed results for similar economies. Utilizing the concepts of deterministic and stochastic convergence, we develop techniques which incorporate endogenously determined break points to test the unit root hypothesis in relative per capita income. The tests provide evidence of deterministic convergence for 10, and stochastic convergence for 14, of the 16 OECD countries. Our findings reveal that World War II is the major cause of the structural shifts in relative output.     

Is per capita real GDP stationary in five southeastern European countries? Fourier unit root test

This study uses the newly developed Fourier unit root test advanced by Enders and Lee (2004, 2009) to investigate the time-series properties of real GDP (Gross Domestic Product) for five Southeastern European countries for the period from 1969 to 2009. The empirical results from several conventional unit root tests indicate that the per capita real GDP for all of the countries studied are non-stationary; however, when Enders and Lee (2004, 2009) Fourier unit root tests are conducted, one rejects the unit root hypothesis of real GDP per capita in all countries under study. These results have important policy implications for these five Southeastern European countries under study.     

Convergence in Per Capita Carbon Dioxide Emissions Among G7 Countries: A TAR Panel Unit Root Approach

The subject of this paper is the examination the convergence of per capita carbon dioxide emissions of the G7 countries during the 1960–2005 period in a nonlinear panel analysis framework. In this approach, first the linearity of the series was tested, and when the linearity was rejected, the threshold autoregressive (TAR) panel unit root test, which splits the data into two regimes, was employed to examine the stationarity properties of the series. Because the null of linearity was rejected in the first step, we tested the stationarity of the series using the TAR panel unit root test. In the TAR panel unit root test, we found that the United Kingdom was the transition country whose per capita carbon dioxide (CO₂) emissions determined the switch from one regime to the other. The results showed that convergence existed in the first regime and divergence, in the second. When we tested whether absolute or conditional convergence existed, we found that the per capita CO₂ emissions were conditionally converging in the first regime.     

Stochastic Divergence or Convergence of Per Capita Carbon Dioxide Emissions: Re-examining the Evidence

This paper revisits the time-series literature on the convergence of per capita carbon dioxide (CO₂) emissions and examines the robustness of previous results. Using a sample of OECD countries for the period 1950–2002 we employ a battery of stationarity and unit root tests including those that allow for cross-sectional dependencies within the panel. We also correct for inaccuracies in previous studies that could result in a trend-stationary series being labelled as converging even if it were actually diverging from the international average. The body of evidence provided by our analysis suggests that per capita CO₂ emissions have not converged among OECD countries during the period under consideration. This finding is of importance to both climate change policy makers and to those who construct climate change models.      

Evidence on the Convergence of Per Capita Income: A Comparison of Founder Members of the Association of South East Asian Nations and the South Asian Association of Regional Cooperation

This paper investigates the per capita income convergence patterns of a set of Association of South East Asian Nations (ASEAN) and South Asian Association of Regional Cooperation (SAARC) countries. We obtained a time‐series analysis for stochastic convergence by applying unit‐root tests in the presence of two endogenously‐determined structural breaks. We then supplemented the results by tests that produced evidence for β convergence. The evidence shows that the relative per capita income series of ASEAN‐5 countries were consistent with stochastic convergence and β convergence, but this was not found for SAARC‐5 countries. For the ASEAN‐5 countries, the structural breaks associated with the world oil crisis and the Asian crisis impacted heavily on the convergence/divergence process.     

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.     

Reexamining the PPP hypothesis: A nonlinear asymmetric heterogeneous panel unit root test

In this study, we re-examine the PPP hypothesis in the light of the new developments in the unit root testing literature. The recent theoretical findings have pointed out that the real exchange rate series exhibit asymmetric nonlinear behavior. A unit root test applied to analyze the PPP hypothesis therefore, should also take into account this asymmetry inherent in the real exchange rate. Different unit root tests that consider the presence of these data features have been developed in the time series literature. However, a true attempt to test the PPP hypothesis should take a panel data approach. To this end, we propose a nonlinear heterogeneous panel unit root test where the alternative hypothesis allows for symmetric or asymmetric exponential smooth transition autoregressive nonlinearity and provide its finite sample properties. We apply our test to the real exchange rates of the 15 European Union countries against the US dollar. While the results of the linear and symmetric nonlinear heterogeneous panel unit root tests are against the PPP hypothesis, the asymmetric nonlinear heterogeneous panel test that we propose gives support for the PPP hypothesis as expected. Therefore, the conclusions drawn from the linear panel unit root tests or the nonlinear panel unit root tests that do not take asymmetry into account might be misleading.     

The behaviour of relative prices in the European Union: A sectoral analysis

Using multivariate unit root test methods, this paper investigates the Purchasing Power Parity (PPP) hypothesis at the sectoral level across six European countries over the last 17 years. Evidence of mean reversion towards PPP is found for the relative prices of some sectors and countries. Mean reversion in relative prices is explained by cross-country and cross-sectoral characteristics such as the distance between countries, nominal exchange rate volatility, differences in GDP per capita, non-tariff barriers, research and development, advertising, industrial concentration and tradeability of the products.     

Per capita output convergence across Asian countries: Evidence from covariate unit root test with an endogenous structural break

This study investigates long-run convergence of per capita output across ten Asian countries over 1960 to 2014 by taking advantage of possible economic growth determinants, which may be responsible for setting Asian countries on a long-term steady-state growth path. We simultaneously examine the presence of output convergence in the region, as well as the statistical significance of these economic growth determinants, by using a unit root test with a stationary covariate. In addition, the study allows for the presence of endogenous structural changes in the time series under investigation in order to capture sharp drops in per capita outputs, which may be brought about by influential economic events, such as serious economic slumps in domestic economies or the global financial crises in 1997–98 and 2008–09. The limiting distribution of the covariate unit root test that permits structural breaks is also derived. The results show significant evidence to support the convergence hypothesis. In particular, asymptotically absolute convergence holds among Hong Kong, Korea, Singapore, and Taiwan. In addition, Thailand shows a convergence tendency in terms of asymptotically relative convergence toward Singapore. Malaysia, Indonesia, and India also turn out to converge toward Hong Kong in an asymptotically relative sense. Certain potential growth determinants, such as the trade/GDP ratio, inflation rate, government expenditure/GDP ratio, and quality of human capital, may help these countries achieve and maintain the long-run convergence process toward the reference countries in the region.     

Nonlinearity and the Unit Root Hypothesis for African Per Capita Real GDP

Once described as an epic center of growth tragedy, African nations have lately achieved relatively rapid growth rates, which have raised hopes that the continent is finally on the path to economic convergence with other emerging economies. However, there is a need to establish whether stabilization policies for the purpose of enhancing the GDP are effective in African countries. One of the means of examining the effectiveness of these policies is through the investigation of the unit root properties of per capita GDP in the continent. This study aims to add to the existing papers on GDP in African countries by investigating the non-stationarity of per capita GDP in 52 African countries, while using a newly proposed nonlinear unit root test. The results suggest that per capita GDP follows the non-stationarity process in half of the entire sample.     

Re-examining the real interest rate parity hypothesis (RIPH) using panel unit root tests with asymmetry and cross-section dependence

This paper investigates the validity of the real interest rate parity hypothesis (RIPH) using a panel unit root approach. For this purpose, first we estimate the possible nonlinear data-generating processes of the real interest rate differential series and using these estimates determine which panel unit root test is better for analyzing the RIPH. To this end, smooth transition autoregressive and threshold autoregressive (TAR) models are estimated for two different panels of countries: G7 and post-Soviet transition economies. The results show that the data displays both strong asymmetry and high transition speed. Therefore, secondly, we propose a new panel unit root test where the alternative is stationary with asymmetric TAR adjustment, and provide their empirical power properties. Finally, we demonstrate that our newly proposed test is able to provide conclusive evidence in favor of the RIPH in contrast to the other panel unit root tests considered.     

Is real GDP per capita a stationary process? Smooth transitions,nonlinear trends and unit root testing

The aim of this article is to provide additional evidence about the order of integration of constant price GDP per capita in a selection of countries. It does so by taking into account the possibility of non-linear deterministic trends and of asymmetric adjustment towards equilibrium. We find evidence of a global stationary ESTAR process around a nonlinear deterministic trend in almost half of the selected countries. These results show that nonlinearities affect real GDP series. By neglecting them, one can draw misleading conclusions from unit root tests. Specifically, the article questions the so-called stylised fact of a near unit root which has so influenced macroeconomic thought over the past two decades.     

Do per capita health care expenditures converge among OECD countries? Evidence from unit root tests with level and trend-shifts

This study examines the stochastic conditional convergence of per capita health care expenditures (PCHCE) among 19 OECD countries over the period 1972–2008. Specifically, newly developed LM and RALS-LM unit root tests with allowance for two endogenously determined structural breaks are employed. The results indicate support for PCHCE convergence among most OECD countries. The results are stronger in more general tests that control for two breaks and nonnormal errors. Panel unit root tests provide additional support for the stochastic convergence of PCHCE.     

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.     

The causal dynamics between renewable energy,real GDP,emissions and oil prices: evidence from OECD countries

This study extends the empirical literature on the determinants of renewable energy consumption in the case of 25 OECD countries for the period 1980–2011. Preliminary analysis suggests the presence of cross-sectional dependence within the panel data. As a result, second-generation panel unit root tests of Smith et al. (2004) and Pesaran (2007) are undertaken to find the respective variables that are integrated of order one. Panel cointegration and error correction modelling reveal that a long-run relationship exists between renewable energy consumption per capita, real GDP per capita, carbon dioxide emissions per capita and real oil prices. The long-run elasticity estimates are positive and statistically significant for real GDP per capita, carbon dioxide emissions per capita and real oil prices. The panel error correction model shows that a feedback relationship exists among the variables.     

Are business cycles stationary fluctuations around a deterministic trend? Empirical evidence from 79 developing countries

There is a large literature that tests the univariate time series properties of the real output series following the seminal work of Nelson and Plosser (1982). Whether or not real output is characterized by a unit root process has important implications. A unit root in real output, for instance, is inconsistent with the notion that business cycles are stationary fluctuations around a deterministic trend. In this paper, we investigate the univariate time series properties of real output for 79 developing countries using the conventional augmented Dickey and Fuller (1979) unit root test, the Zivot and Andrews’ (1992) one structural break unit root test, and the Lumsdaine and Papell (1997) two structural breaks unit root test. Our main finding is that, for 40 countries, real output is stationary around a trend. This indicates that business cycles are stationary fluctuations around a deterministic trend for only 51% of the developing countries in our sample.     

Regime-switching purchasing power parity in Latin America: Monte Carlo unit root tests with dynamic conditional score

We suggest a Monte Carlo simulation-based unit root test of the purchasing power parity theory for Latin American countries. Under the null hypothesis, we use a Markov regime-switching (MS) model with unit root in the conditional location and MS volatility dynamics. Under the alternative hypothesis, the proposed test incorporates Markov regime-switching autoregressive moving average (MS-ARMA) plus MS volatility dynamics. Under both the null and alternative hypotheses, one of the volatility models estimated is Beta-t-EGARCH, which is a recent dynamic conditional score volatility model. We use data on real effective exchange rate time series for 14 Latin American countries. For each country, we estimate by Monte Carlo simulation the critical values of the unit root test. We provide an economic discussion of the unit root test results and also study the robustness of MS-ARMA plus MS volatility with respect to smooth transition autoregressive models with Fourier function.     

Is income converging in China?

This study adopts a flexible Fourier unit‐root test proposed by Enders and Lee (2012) to revisit the tendency towards convergence in real per capita income among provinces after economic reform in China. When a data‐generating process is non‐linear, a Fourier series not only allows for the possibility of an unknown number of structural breaks with unknown forms but also allows for the use of a low‐frequency component to capture multiple changes. Contrary to what the linear statistics suggest, our results from a flexible unit‐root test indicate that China's eastern and western regions are converging to their own specific steady states.     

Predictability within the energy consumption–economic growth nexus: Some evidence from income and regional groups

In re-examining the nexus between energy consumption and economic growth through the predictability framework, we adopt a panel data predictive regression model to examine the possibility of growth, conservative, feedback, or neutrality hypotheses for 135 countries. A predictive regression model is fitted to panels of countries on the basis of location and level of economic development. Findings suggest strong support for the neutrality hypothesis. A developing economy panel (90 countries) favours the conservative hypothesis, although a panel of 32 lower middle-income countries suggests that energy consumption per capita predicts real GDP per capita. These forecasts could provide future policy directions.