A general procedure for fractional integration and structural breaks at unknown points in time is used, which allows for different orders of integration and deterministic components in each subsample. First, the procedure is extended to the non-linear case, and it is shown by means of Monte...

This paper examines aggregate money demand relationships in five industrial countries by employing a two-step strategy for testing the null hypothesis of no cointegration against alternatives which are fractionally cointegrated. Fractional cointegration would imply that, although there exists a...

This paper proposes a model of the US unemployment rate which accounts for both its asymmetry and its long memory. Our approach introduces fractional integration and nonlinearities simultaneously into the same framework, using a Lagrange Multiplier procedure with a standard null limit...

Monthly seasonally unadjusted data can exhibit roots with possibly fractional orders of integration, corresponding to the monthly but also to the quarterly and to the long-run or trending components of the series. In this paper we use a procedure which is suitable to test simultaneously for the...

This paper examines historical data on daily real wages in England for the time period 1260-1994 by means of new statistical techniques suitable for modelling long memory both at the long run and the cyclical frequencies. Specifically, it uses a procedure due to Robinson (1994) which is based,...

This paper examines a version of the tests of Robinson (1994) that enables one to test models of the form (1-Lk)dxt = ut, where k is an integer value, d may be any real number, and ut is I(0). The most common cases are those with k = 1 (unit or fractional roots) and k = 4 and 12 (seasonal unit...

In this paper we examine aggregate money demand relationships in five industrial countries using a two-step strategy for testing the null hypothesis of no cointegration against alternatives that are fractionally cointegrated. Fractional cointegration would imply that, although there exists a...

This paper analyses the long memory properties of quarterly real output per capita in the US (1948Q1 - 2008Q3) using non-parametric, semi-parametric and parametric techniques. The results vary substantially depending on the methodology employed. Evidence of mean reversion is obtained in a...

This paper proposes a very general time series framework to capture the long-run behaviour of financial series. The suggested model includes linear and non-linear time trends, and stationary and nonstationary processes based on integer and/or fractional degrees of differentiation. Moreover, the...