In this paper, we analyse the behaviour of regression-based tests for seasonal unit roots when the error is periodically heteroscedastic. We show, using the case of quaterly data to illustrate, that the limiting null distribution of tests for unit roots at the zero and Nyquist frequencies are...

A sequential procedure for determination of trend degree and testing for unit root is introduced; its properties are investigated by Monte Carlo experiments. We compare the performance of Augmented Dickey-Fuller tests and the GLS tests of Elliott, Rothenberg and Srock (1996), in both cases with lag...

This paper examines the effects of union decline in Britain on changes in earnings dispersion between 1983 and 1995. As part and parcel of the exercise, the effects of changes in the wage gap and the variance gap are also calculated. Detailed findings are provided by gender and broad sector,...

Taking as our point of departure a model proposed by David Card (2001), we suggest new methods for analyzing wage dispersion in a partially unionized labor market. Card's method disaggregates the labor population into skill categories, which procedure entails some loss of information....