There is a sizeable literature that tests for weak-form efficiency in commodity and energy spot and futures 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 b...

This study tests the random walk hypothesis for the Indian stock market. Using 19 years of monthly data on six indices from the National Stock Exchange (NSE) and the Bombay Stock Exchange (BSE), this study applies three different unit root tests with two structural breaks to analyse the random walk hypothesis. We find that unit root tests that allow for two structural breaks alone are not able ...

The theme of instability or breaks in macroeconomic series has attracted considerable attention over the last several decades. There are a large number of tests for structural changes or the stability of parameters. We focus the review of unit-root tests, unit-root tests including possible structural breaks, and time-varying parameter literature. Unit-root tests, which concentrate on the studyi...

Endogenous variables in structural models of agricultural commodity markets are typically treated as stationary. Yet, tests for unit roots have rather frequently implied that commodity prices are not stationary. This seeming inconsistency is investigated by focusing on alternative specifications of unit root tests. We apply various specifications to Illinois farm prices of corn, soybeans, barro...

In this paper, we consider a sieve bootstrap for the test of a unit root in models driven by general linear processes. The given model is ...rst approximated by a ...nite autoregressive integrated process of order increasing with the sample size, and then the method of bootstrap is applied for the approximated autoregression to obtain the critical values for the usual unit root tests. The resul...

Abstract T his paper is to convince the usage of the nonlinear unit root tests when dealing with a nonlinear model. To do so, the stationary test for variables in a model titles “Fiscal Reaction Function in Iran” has been applied according to both the ordinary and the Nonlinear Dickey-Fuller (NDF) tests. Results show that while variables under investigation are stationary ...

Rice plays an especial role in Iranian households' nutrition basket. The volatilities of its price during recent years caused consumers' dissatisfaction. This paper investigates spillover effects of price volatilities (at the wholesale and retail levels) in the Guilan Province rice market. The Generalized Autoregressive Conditional Hetroscedasitic (GARCH) model was used for the monthly time per...

We consider the bootstrap method for the covariates augmented DickeyFuller (CADF) unit root test suggested in Hansen (1995) which uses related variables to improve the power of univariate unit root tests. It is shown that there are substantial power gains from including correlated covariates. The limit distribution of the CADF test, however, depends on the nuisance parameter that represents the...

Applications of panel unit root tests have become commonplace in empirical economics, yet there are ambiguities as how best to interpret the test results. This note clarifies that rejection of the panel unit root hypothesis should be interpreted as evidence that a statistically significant proportion of the units are stationary. Accordingly, in the event of a rejection, and in applications wher...

Monte Carlo evidence [Evans (1991)] indicates that when speculative bubbles are collapsible, the traditional cointegration approach based on unit root tests has some serious drawbacks. We propose in this paper an alternative approach to test such bubbles. We demonstrate that the suggested test has some advantages over the traditional unit root based tests, especially for bubbles that are collap...