Long-range persistence in volatility is widely modelled and forecasted in terms of the so-called fractional integrated models. These models are mostly applied in the univariate framework, since the extension to the multivariate context of assets portfolios, while relevant, is not...

This paper focuses on nominal exchange rates, specifically the US dollar rate vis-à-vis the Euro and the Japanese Yen at a daily frequency. We model both absolute values of returns and squared returns using long-memory techniques, being particularly interested in volatility modelling and...

Fractionally integrated processes have become a standard class of models to describe the long memory features of economic and financial time series data. However, it has been demonstrated in numerous studies that structural break processes and non-linear features can often be confused as being...

This paper 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 general, and, in particular, encompasses the...

Semiparametric estimation of the memory parameter is studied in models of fractional integration in the nonstationary case, and some new representation theory for the discrete Fourier transform of a fractional process is used to assist in the analysis. A limit theory is developed for an...

Deciding whether a time series that appears nonstationary is in fact fractionally integrated or subject to structural change is a difficult task. However, various tests have recently been introduced for distinguishing long memory from level shifts and nonlinearity. In this paper, three testing...

Over the last years there has been considerable interest in the application of long memory time series models in economics using ARFIMA models. Nowadays, the most popular estimator of the difference parameter in economic applications is that proposed by Geweke and Porter-Hudak (GPH) although has...

In many fields of economic analysis the order of integration of some economic magnitudes is of particular interest. Among other aspects, the order of integration determines the degree of persistence of that magnitude. The rate of inflation is a very interesting example because many contradictory...

In short-term evolution analysis, the economic time series are contamined by different types of noises which need to be erased in order to extract a trend signal. In the last years there has been increasingly developed some methods to estimate unobserved components based on the assumption that...

This paper estimates a long memory volatility model for 16 agricultural commodity futures returns from different futures markets, namely corn, oats, soybeans, soybean meal, soybean oil, wheat, live cattle, cattle feeder, pork, cocoa, coffee, cotton, orange juice, Kansas City wheat, rubber, and...