We investigate the power and size performance of unit root tests when the true data generating process undergoes Markov regime-switching. All tests, including those robust to a single break in trend growth rate, have very low power against a process with a Markov-switching trend growth rate as...

The fact that weak instruments lead to spurious inference is now widely recognized. In this paper we ask whether spurious inference occurs more generally in weakly identified models. To distinguish between models where spurious inference will occur from those where it does not, we introduce the...

Several recent papers conclude that U.S. real GDP is trend stationary, implying that all shocks are transitory and the long run path is deterministic. These inferences fail to take into account two problems: the distortion of test size in finite samples due to data-based model selection and the...