Researchers desire powerful tests for unit roots. This paper derives the family of asymptotically most powerful tests for unit roots when the initial condition is drawn from its unconditional distribution under the alternative. This enables both the examination of previously proposed statistics...

This article proposes a new forecast combination method that lets the combination weights be driven by regime switching in a latent state variable. An empirical application that combines forecasts from survey data and time series models finds that the proposed regime switching combination scheme...