We demonstrate that the constant variance assumption in the Markov-switching Augmented Dickey-Fuller (ADF) test proposed by Hall, Psaradakis and Sola (1999) may result in the misjudgement of bubbles. Upon relaxing this assumption to allow for regime-varying error variances in the...

It is well-known that interest rates are extremely persistent, yet they are best modeled and understood as stationary processes. These properties are contradictory in the workhorse Gaussian affine term structure model in which the persistent data often result in unit roots that imply...

A number of recently published papers have focused on the problem of testing for a unit root in the case where the driving shocks may be unconditionally heteroskedastic. These papers have, however, assumed that the lag length in the unit root test regression is a deterministic function of the...