This paper studies fractional processes that may be perturbed by weakly dependent time series. The model for a perturbed fractional process has a components framework in which there may be components of both long and short memory. All commonly used estimates of the long memory parameter (such as...

Fixed effects estimators in nonlinear panel models with fixed T usually suffer from inconsistency because of the incidental parameters problem first noted by Neyman and Scott (1948). Moreover, even though T grows at the same rate as n, they are asymptotically biased and therefore the associated...

Parametric copulas are shown to be attractive devices for specifying quantile autoregressive models for nonlinear time-series. Estimation of local, quantile-specific copula-based time series models offers some salient advantages over classical global parametric approaches. Consistency and...

Nonlinearities in the drift and diffusion coefficients influence temporal dependence in scalar diffusion models. We study this link using two notions of temporal dependence: beta-mixing and rho-mixing. We show that beta-mixing and rho-mixing with exponential decay are essentially equivalent...

Let H be an infinite-dimensional real separable Hilbert space. Given an unknown mapping M : H H that can only be observed with noise, we consider two modified Robbins-Monro procedures to estimate the zero point o H of M. These procedures work in appropriate finite dimensional sub-spaces of...