The purpose of this study is to investigate the asymptotics of a first order auto regressive unit root process, AR(1). The goal is to determine which tests could be used to test for the presence of a unit root in a first order auto regressive process. A unit root is present when the root of the characteristic equation of this process equals unity. In order to test for the presence of a unit roo...

Unit root tests for time series with level shifts are considered. The level shift is assumed to occur at a known time point. In contrast to some other proposals the level shift is modeled as part of the intercept term of the stationary component of the data generation process which is separated from the unit root component. In this framework simple shift functions result in a smooth transition ...

It is known that unit root test statistics may not have the usual asymptotic properties when the variance of innovations is unstable. In particular, persistent changes in volatility can cause the size of unit root tests to differ from the nominal level. In this paper we propose a class of modified unit root test statistics that are robust to the presence of unstable volatility. The modification...

Although the impacts of structural instability on testing for unit root have been studied extensively for univariate time series, such impacts on panel data unit root tests are still relatively unknown. A major issue is the choice of model in accommodating different types of break (instability) prior to testing for unit root. Specifically, researchers must specify a potential break in the inter...

Using local-to-unity detrending, a modified momentum-threshold autoregressive test is derived to allow the unit root hypothesis to be tested against an alternative of asymmetric stationarity about a deterministic trend. Monte Carlo evidence is presented to show the increased power of the proposed test in the presence of asymmetric adjustment relative to the familiar Dickey-Fuller (1979) test an...

This paper applies univariate and panel data unit root tests to annual panel data for 182 countries over the period 1979-2000 to examine the stationarity properties of per capita energy consumption. The univariate unit root test can only reject the unit root null for 29 per cent of the countries at the 10 per cent level or better without a trend and 37 per cent of the countries at the 10 per ce...

A new resampling procedure, the continuous-path block bootstrap, is proposed in the context of testing for integrated (unit root) time series. The continuous-path block bootstrap (CBB) is a nonparametric procedure that successfully generates unit root integrated pseudo time series retaining the important characteristics of the data, e.g., the dependence structure of the stationary process drivi...

We combined recent developments in univariate and multivariate unit root testing in order to construct a more-powerful panel unit root test. We extended the GLS-detrending procedure of Elliott, Rothenberg, and Stock (1996) to a panel Augmented Dickey-Fuller test. The finite sample power properties of the new test demonstrate a very large gain when compared to existing tests, especially for smal...