The main objective of this paper is to shed light on the problem of low power for the Dickey-Fuller type unit root tests. It is argued that the low power is primarily due to the non-nestedness of the Autoregressive (AR(1)) and the Unit Root (UR(1)) models. The paper proposes an AR(1) model with Conditional Heterogeneity (ARCHET(1)) which parametrically encompasses the UR(1) model. A number of s...

The effects of colonisation of roots by arbuscular mycorrhizal fungi (AMF) on soil respiration, plant growth, nutrition, and soil microbial communities were assessed using a mycorrhiza-defective tomato (Solanum lycopersicum L.) mutant and its mycorrhizal wild-type progenitor. Plants were grown in rhizocosms in an automated respiration monitoring system over the course of the experiment (79 days...

This study is held in order to determine whether some Middle Eastern countries have converged EU terms of economy and politics as dimensions globalization. Existence any convergence tested via Harvey ve Leybourne (2008) linearity tests. It has been deduced that Quwait EU-27 average from the point economic globalization country also EU-15 social Similarly, Saudi Arabia EU-9 avearges socail Egypt...

This paper investigates the effects of consistent and inconsistent long-run variance estimation on a unit root test based on the generalization of the von Neumann ratio. The results from the Monte Carlo experiments suggest that the tests based on an inconsistent estimator have less size distortion and more stability of size across different autocorrelation speciÞcations as compared to the tests...

We investigate the performance of some homogenous first and second generation panel unit root tests under alternative forms of cross sectional dependence. We formalize contemporaneous correlation through factor models, spatial autoregressive error models and combinations thereof. Our findings confirm that while the first generation test of Levin, Lin, and Chu (2002) suffers from substantial siz...

There is a growing literature on unit root testing in threshold autoregressive models. This paper makes two contributions to the literature. First, an asymptotic theory is developed for unit root testing in a threshold autoregression, in which the errors are allowed to be dependent and heterogeneous, and the lagged level of the dependent variable is employed as the threshold variable. The asymp...

The Enders and Granger (1998) unit-root test against stationary alternatives with asymmetric adjustment is applied to the extended Nelson and Plosser dataset. The test rejects roughly as frequently as does the ADF test on these data. In only one of these cases, for the S&P500 index, does further testing suggest that the adjustment mechanism is asymmetric.