Many researchers use GARCH models to generate volatility forecasts. We show, however, that such forecasts are too variable. To correct for this, we extend the GARCH model by distinguishing two regimes with different volatility levels. GARCH effects are allowed within each regime, so that our...

Most economists intuitively consider purchasing power parity (PPP) to be true. Nevertheless, quite surprisingly, the empirical literature is not very supportive for PPP. In this paper, however, we find evidence in favor of PPP using a new test. The test is embedded in a Markov regime-switching...

The random walk is often used to model exchange rates. According to the Lucas critique, however, policy shifts may lead to breaks in the trend of exchange rates and hence to long swings. We use a Markov regime-switching model to allow for such swings and we reject the random walk in favor of the...

In this paper we propose consistent cointegration tests, and estimators of a basis of the space of cointegrating vectors, that do not need specification of the data-generating process, apart from some mild regularity conditions, or estimation of structural and/or nuisance parameters. This...

We propose a class of distribution-free rank-based tests for the null hypothesis of a unit root. This class is indexed by the choice of a reference density g, which needs not coincide with the unknown actual innovation density f. The validity of these tests, in terms of exact finite sample size,...