It is generally believed that for the power of unit root tests, only the time span and not the observation frequency matters. In this paper we show that the observation frequency does matter when the high-frequency data display fat tails and volatility clustering, as is typically the case for...

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...

We analyze the time-dependence of exchange rate correlations using a new multivariate GARCH model. This model consists of two parts. First, we transform the exchange rate changes into their principal components and specify univariate GARCH models for all components. Second, we use the inverse of...

It is generally believed that for the power of unit root tests, only the time span and not the observation frequency matters. In this paper, we show that the observation frequency does matter when the high-frequency data display fat tails and volatility clustering, as is typically the case for...