Benoit Mandelbrot, mathématicien et savant multidisciplinaire, s'intéressa très tôt dans sa carrière à l'étude statistique des données économiques et financières et fut à l'origine de nombreuses idées importantes dans la modélisation statistique des risques financiers, sujet qui le...

This paper proposes a new fractional model with a time-varying long-memory parameter. The latter evolves nonlinearly according to a transition variable through a logistic function. We present a LR-based test that allows to discriminate between the standard fractional model and our model. We...

In ESTAR models it is usually quite difficult to obtain parameter estimates, as it is discussed in the literature. The problem of properly distinguishing the transition function in relation to extreme parameter combinations often leads to getting strongly biased estimators. This paper proposes a...