This paper proposes similar unit root testing procedures for both homogenous and heterogeneous dynamic panel data models, based on least squares estimates and assuming that the time dimension of the panel data is fixed. It is shown that the limiting distribution of the tests id standard normal.

This paper considers regression-based test criteria for the hypothesis of conditional variance nonstationary in the logarithmic family of GARCH processes. The tests are based on teh ARMA representations that appropriate nonlinear transformations of GARCH-type processes admit. Simulation...

This paper questions the widespead practice of assessing the hypothesis of long-run fiscal policy sustainability by means of conventional unit-root tests that do not allow for the possible impact of regime shifts. Using the Greek economy as a model case, the Zivot- Andrews squential...

An approximation to order T-2 is obtained for the bias of the least-squares estimator in the stationary ARX model which yields generalisations of Kendall's and White's classic results for particular variants of AR(1) models. The results show that generally the second-order approximation is...