The power of asymmetric unit root tests under threshold and consistent-threshold estimation

The asymmetric unit root tests of Enders and Granger (Journal of Business and Economic Statistics, 16, 304-11, 1998) are examined using consistent threshold estimation and the original two-step procedure. In contrast to earlier studies, the ability of the tests to jointly reject the unit root and symmetry hypotheses is examined, thus permitting a fuller analysis of the tests' properties. Whilst the threshold autoregressive test is found to have little power in either its consistent or original forms, the consistent momentum-threshold autoregressive test is found to exhibit high power against a range of plausible alternatives when using newly derived critical values.