This paper uses the approach of Im, Pesaran and Shin (2003) to propose seasonal unit root tests for dynamic heterogeneous panels based on the means of the individuals HEGY test statistics. The standardised t-bar and F-bar statistics are simply averages of the HEGY tests across groups. These...

This paper presents two alternative methods for modifying the HEGY-IPS test in the presence of cross-sectional dependency. In general, the bootstrap method (BHEGY-IPS) has greater power than the method suggested by Pesaran (2007) (CHEGY-IPS), although for large T and high degree of...

We investigate the effects of outliers on the KPSS tests. We find that for nonstationary series outliers induce spurious stationarity by lowering the power of these tests. The empirical size of these tests is also found to be sensitive to the location of the outlier.

The panel variant of the KPSS tests developed by Hadri (2000) for the null of stationarity suffers from size distortions in the presence of cross section dependence. However, applying the bootstrap methodology we find that these tests are approximately correctly sized.

We examine the effects of seasonal adjustment filters on the size and power of ADF and PP residual-based cointegration tests via a Monte Carlo and an empirical application. Our results indicate that the use of filters distorts the size and reduces the power of these tests.

This paper uses the approach of Im, Pesaran and Shin (2003) to propose seasonal unit root tests for dynamic heterogeneous panels based on the means of the individuals HEGY test statistics. The standardised t-bar and F-bar statistics are simply averages of the HEGY tests across groups. These...