No CrossRef data available.
Published online by Cambridge University Press: 11 February 2009
This paper considers unit root tests based on Mestimators. The asymptotic theory for these tests isdeveloped. It is shown how the asymptoticdistributions of the tests depend on nuisanceparameters and how tests can be constructed that areinvariant to these parameters. It is also shown thata particular linear combination of a unit root testbased on the ordinary least-squares (OLS) estimatorand on an M estimator converges to a normal randomvariate. The interpretation of this result isdiscussed. A simulation experiment is described,illustrating the level and power of different unitroot tests for several sample sizes and datagenerating processes. The tests based on Mestimators turn out to be more powerful than theOLS-based tests if the innovations arefat-tailed.