Conventional unit root tests are known to be unreliable in the presence of permanent volatility shifts. In this paper, we propose a new approach to unit root testing which is valid in the presence of a quite general class of permanent variance changes which includes single and multiple (abrupt...

We show that changes in the innovation covariance matrix of a vector of series can generate spurious rejections of the null hypothesis of co-integration when applying standard residual-based co-integration tests. A bootstrap solution to the inference problem is suggested which is shown to...

type="main" xml:id="jtsa12074-abs-0001" <title type="main">Abstract</title> <p>We provide a fast algorithm for calculating the fractional difference of a time series. In standard implementations, the calculation speed (number of arithmetic operations) is of order T-super-2, where T is the length of the time series. Our...</p>

type="main" xml:id="jtsa12100-abs-0001"This article proves consistency and asymptotic normality for the conditional-sum-of-squares estimator, which is equivalent to the conditional maximum likelihood estimator, in multivariate fractional time-series models. The model is parametric and quite...