Seasonal Unit Root Tests Under Structural Breaks*

Seasonal Unit Root Tests Under Structural Breaks

In this paper, several seasonal unit root tests are analysed in the context of structural breaks at known time and a new break corrected test is suggested. We show that the widely used HEGY test as well as an LM variant thereof are asymptotically robust to seasonal mean shifts of finite magnitude. In finite samples, however, experiments reveal that such tests suffer from severe size distortions...

Structural Breaks and Unit Root Tests for Short Panels

In this paper we suggest panel data unit root tests which allow for a potential structural break in the individual e¤ects and/or the trends of each series of the panel, assuming that the time-dimension of the panel, T , is ...xed. The proposed test statistics consider for the case that the break point is known and for the case that it is unknown. Monte Carlo evidence suggests that they have siz...

Unit Root Tests and Structural Breaks: A Survey with Applications

The theme of unit roots in macroeconomic time series have received a great amount of attention in terms of theoretical and applied research over the last three decades. Since the seminal work by Nelson and Plosser (1982), testing for the presence of a unit root in the time series data has become a topic of great concern. This issue gained further momentum with Perron’s 1989 paper which emphasiz...

Regression-based seasonal unit root tests

The contribution of this paper is three-fold. Firstly, a characterisation theorem of the sub-hypotheses comprising the seasonal unit root hypothesis is presented which provides a precise formulation of the alternative hypotheses against which regression-based seasonal unit root tests test. Secondly, it proposes regressionbased tests for the seasonal unit root hypothesis which allow a general se...

Purchasing Power Parity Hypothesis In OIC Countries: Evidence From Panel Unit Root Tests With Heterogeneous Structural Breaks