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...

We propose in this article a two-step testing procedure of fractional cointegration in macroeconomic time series. It is based on Robinson's ("Journal of the American Statistical Association", Vol. 89, p. 1420) univariate tests and is similar in spirit to the one proposed by Engle & Granger...

This paper introduces a multivariate long-memory model with structural breaks. In the proposed framework, time series exhibit possibly fractional orders of integration which are allowed to be different in each subsample. The break date is endogenously determined using a procedure which minimises...

This article deals with the analysis of structural breaks in the context of fractionally integrated models. We assume that the break dates are unknown and that the different sub-samples possess different intercepts, slope coefficients and fractional orders of integration. The procedure is based...

In this paper, we test if stock index prices follow random walks in the Spanish Stock Market by means of variance ratios. We find strong evidence of positive autocorrelation for both IGBM and IBEX35 daily returns until 1977, but not after that date. Although weekly and monthly index positive...

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...

In a recent paper, Yoon (2003) shows that the Stochastic Unit Root (STUR) model is closely related to long memory processes, and, in particular, that it is a special case of an I(d) process, with d = 1.5. In this paper we further examine this issue by using parametric and semiparametric...

In this paper fractionally integrated ARIMA (ARFIMA) models are estimated using an extended version of Nelson and Plosser’s (1982) dataset. The analysis employs Sowell’s (1992) maximum likelihood procedure. Such a parametric approach requires the model to be correctly specified in order for...

In this paper we use a statistical procedure which is appropriate to test for deterministic and stochastic (stationary and nonstationary) cycles in macroeconomic time series. These tests have standard null and local limit distributions and are easy to apply to raw time series. Monte Carlo...

In this article we estimate the order of integration of the volatility process of several exchange rates and stock returns using fractionally integrated semiparametric techniques,namely a local Whittle semiparametric estimator. The results suggest that all series can be well described in terms...