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.     

ASIAN REAL EXCHANGE RATES AND OIL PRICES: A COINTEGRATION ANALYSIS UNDER STRUCTURAL BREAKS

We examine the long‐run relationship between Asian real exchange rates and oil prices in the presence of structural breaks. The relevance of considering breaks is demonstrated by utilizing the Johansen et al. procedure that allows for up to two predetermined breaks. Using conventional tests that do not consider breaks reveals no evidence of cointegration. However, the Johansen et al. procedure clearly demonstrates the importance of considering breaks and provides strong support for a stable long‐run relationship in all but Japan and the Philippines. Moreover, the results suggest evidence of bi‐directional causality in Malaysia and Thailand, uni‐directional causality from exchange rates to oil prices in Korea, the Philippines, and Singapore, uni‐directional causality from oil prices to the exchange rate in Indonesia, and no evidence of causality in Japan.     

Covariate unit root tests under structural change and asymmetric STAR dynamics

In this paper, we intend to develop a new unit root testing procedure. The novelty of this methodology includes (1) accommodating possible trend breaks of unknown number, unknown dates, and unknown form by employing the Fourier form without directly estimating such breaks; (2) considering possible asymmetric STAR adjustments under the alterative; and (3) utilizing related covariates to boost the testing power. The limiting distribution of the test is derived, and the asymptotic critical values are tabulated. Simulation experiments show that the test can deliver robust size for various breaks commonly seen in economic analysis and enjoy high power property, even in small sample sizes encountered in empirical studies. The usefulness of the test is illustrated in an empirical study on the issue of debt sustainability in 18 OECD countries.     

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.     

A Test of Long-run Purchasing Power Parity Allowing for Structural Breaks*

If exchange rates and prices are integrated processes, standard econometric tests of the purchasing power parity (PPP) hypothesis may be biased towards rejection. This paper avoids this problem by using the Engle and Granger (1987) theory of cointegrated processes. If the absolute version of purchasing power parity is true, and nominal exchange rates and prices are integrated processes, inter-commodity arbitrage should ensure that the real exchange rate is stationary. The stationarity hypothesis is tested using Australian real exchange rate data for the 1890–1984 period We find that the effective real exchange rate cannot be modelled as a stationary process and therefore reject the absolute version of PPP. We also employ a test for structural breaks due to, for instance, the oil price shock and find mixed results. Another interpretation of our results is that the real exchange rate was affected by a series of permanent, real shocks during the sample period     

LM cointegration tests allowing for an unknown number of breaks: implications for the forward rate unbiasedness hypothesis

This article extends the Lagrange multiplier (LM) cointegration test proposed by Westerlund and Edgerton (WE 2007) by allowing for an unknown number of breaks. Monte Carlo simulations provide two main results. First, a loss of power in the LM cointegration tests is detected when potential multiple breaks are ignored. Second, the modified testing procedures do not affect the asymptotic distribution and major properties of the tests of WE under the null, but noticeably increase their testing power in presence of multiple breaks. We also provide empirical applications of the proposed tests for the forward rate unbiasedness hypothesis (FRUH). The results reveal that the FRUH does hold when the effects of the multiple structural breaks are taken into account.     

Bayesian model averaging and identification of structural breaks in time series

Bayesian Model Averaging (BMA) is used for testing for multiple break points in univariate series using conjugate normal-gamma priors. This approach can test for the number of structural breaks and produce posterior probabilities for a break at each point in time. Results are averaged over specifications including: stationary; stationary around trend and unit root models, each containing different types and number of breaks and different lag lengths. The procedures are used to test for structural breaks on 14 annual macroeconomic series and 11 natural resource price series. The results indicate that there are structural breaks in all of the natural resource series and most of the macroeconomic series. Many of the series had multiple breaks. Our findings regarding the existence of unit roots, having allowed for structural breaks in the data, are largely consistent with previous work.     

Cointegration and causal relationships among steel prices of Mainland China, Taiwan, and USA in the presence of multiple structural changes

Variation in the price of steel is an important factor to take into consideration when discussing cost control and management decisions in the construction industry. We employ various conventional and advanced econometrics methods to examine the interrelationships of steel prices in three related markets during the time period June 2002 to May 2010: Mainland China (CH), Taiwan (TW), and the United States (US). We adopt the Gregory and Hansen (GH) test and regime-switching (RS) model for cointegration, both of which accommodate endogenous structural break(s), to produce a more accurate analysis of a period in the presence of structural change(s). The empirical result of the RS cointegration test with respect to multiple structural breaks suggests a long-run equilibrium relationship among the three variables considered. This finding differs from the result of the GH test but confirms the result of the conventional Johansen test. Furthermore, the results of the Granger causality test indicate that both CH and US steel prices have great influence on the TW steel price; the Taiwanese steel market is closely linked with China and US steel markets in the long run.     

The Interdependence of Australian and Foreign Real Interest Rates

We assess the interdependence of the Australian and foreign (USA, Japan, UK, Canada, Germany, NZ) short-term real rates of interest using a quarterly time series: 1970(1) to 1997(4). Applying Zivot and Andrews (1992) tests for stationarity subject to structural breaks we find all series to be 1(1). Structural breaks occurring in each series at different times are explained by policy changes, institutional characteristics or shocks such as the second oil crisis. Conventional bivariate cointegration tests (without breaks) provide limited evidence of interdependence, however using the Gregory Hansen (1996a,b) technique it is clear that foreign and Australian rates are interrelated once structural breaks are accommodated. Multivariate cointegration and error correction modelling confirm this finding. Policy implications are indicated.     

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.     

On the application of the rank tests for nonlinear cointegration to PPP: The case of Papua New Guinea

Much interest has been paid recently to the nonlinear cointegrating relations existing among economic variables. Various testing procedures are already available to test for the existence of nonlinear cointegration. For example, Breitung (2001) proposes rank tests and his testing procedure has been broadly applied. In this study, we warn against a blind application of the rank cointegration tests, particularly to economic variables that evidence certain behavior. As an illustration, we employ the nominal exchange rates and relative prices of Papua New Guinea against her major trading partners with the objective of testing the validity of purchasing power parity for the country. Our simulation results also confirm our warnings. Additionally, we provide some simple solutions to the problem we encounter herein.     

进口的经济增长效应——基于趋势突变的协整检验分析

当时间序列存在结构突变时,会降低单位根检验和协整检验的检验势.通过对进口对于经济增长的影响作用进行实证分析,可以得到进口没有发挥出应有的促进经济增长的作用;结构突变理论比较适合于研究转型期的中国经济问题的结论.     

Testing for structural breaks in factor loadings: An application to international business cycle

This paper proposes the implementation of the SupWald test of Andrews (1993) to detect structural breaks in the loadings of a static factor model. The procedure is illustrated by testing for structural breaks in the common factors of GDP growth series for a sample of advanced countries from 1950 until 2006.     

A note on the stability of real interest rates in Australia

The stability (stationarity) of real interest rates and surveys of expected inflation in Australia is analyzed over the period 1993(10) to 2001(10). We find that the real yields on Australian 2-, 5-, and 10-year bonds are stationary in levels whereas the real overnight cash and the bank-accepted bills (BABs) 90-day real rates are stationary subject to structural breaks occurring in September 1994 and October 1994, respectively. These breaks were identified by applying tests proposed by Nunes et al. [Oxf. Bull. Econ. Stat. 59 (1997) 435]. An application of the Nunes test to the surveyed expected inflation series points to a structural break in this series in January 1998.Our results indicate that while real long-term bond yields in Australia are relatively stable, short-term yields and expected inflation are susceptible to domestic policy changes and international influences.     

Is Asian per capita GDP panel stationary?

The goal of this paper is to examine whether per capita GDP for 15 Asian countries is panel stationary. We apply a panel test for stationarity that allows for multiple structural breaks developed by Carrion-i-Silvestre et al. (Econ J 8: 159–179, 2005). Our main findings are: (1) when we apply conventional tests, such as the ADF and KPSS univariate tests without structural breaks, we find little evidence for stationarity; (2) when we apply the KPSS univariate test with multiple structural breaks, we find evidence of stationarity for 10 out of 15 countries; and (3) when we apply the KPSS panel test with multiple structural breaks, we find overwhelming evidence of panel stationarity of per capita real GDP for different panels of Asian countries.      

Removal of farm subsidies in a regional economy: a computable general equilibrium analysis

There are a number of studies that examine the purchasing power parity (PPP) hypothesis. The empirical findings from the extant literature for the PPP hypothesis are mixed. This article applies univariate and panel Lagrange Multiplier (LM) unit root tests with one and two structural breaks to real exchange rates for 15 Asian countries. The univariate LM unit root tests find evidence of PPP for two-thirds of the sample. The results from the panel LM unit root test support long-run PPP for the Asian countries in the sample. The results from the LM panel unit root tests differ from those of existing panel unit root tests of PPP for Asian countries that have not allowed for the existence of structural breaks.     

Testing for a unit root with covariates against nonlinear alternatives

This paper proposes a new procedure for testing the unit root null against stationary but nonlinear alternatives. This test can be viewed as a generalization of the one developed by Kapetanios et al. (2003) (the KSS test) by incorporating stationary covariates. The asymptotic distribution of the test is derived and the asymptotic critical values are tabulated. A set of Monte Carlo simulations show that our test generally achieves large power improvements over the KSS test. An illustrated empirical application indicates that our proposed test is able to unveil more evidence than the KSS test in favor of no unit root of real exchange rates in 15 Asian countries.     

An analysis of multiple structural breaks in US relative farm prices

The movement of farm prices relative to other commodity prices is analysed for the period 1913:01 to 2003:12, investigating the number and time of structural breaks and discussing likely causes of structural breaks in the relative farm prices. Bai and Perron's (1998, 2003) multiple structural change test with a dynamic programming algorithm is used. This test makes it possible to have an efficient computation of the estimates of the break points as global minimizers of the sum of squared residuals. We find six structural breaks when we consider only the mean process and two breaks when we consider the mean and autoregressive processes. Possible causes for these breaks are discussed.     

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.     

中国宏观经济时序的平稳性再考察——内生突变与平滑转换

对宏观变量是由确定性趋势所主导还是由随机趋势所主导的区分涉及预测精度以及潜在数据生成过程的认知理念等问题,本文意在指出若将结构变化包括在内单位根观念的认知需要扭转。具体地,文章用傅里叶级数拟合经济时序,与先前研究不同的是在处理突变方式上把对突变位置和突变方式的估计转化为恰当频率的选择问题。对中国15个代表性宏观时序的考察表明,视大多宏观变量为平滑转换的趋势平稳过程更为合适。