In this paper we tackle the problem of fast rates in time series forecasting
from a statistical learning perspective. In a serie of papers (e.g. Meir 2000,
Modha and Masry 1998, Alquier and Wintenberger 2012) it is shown that the main
tools used in learning theory with iid observations can be extended to the
prediction of time series. The main message of these papers is that, given a
family of predictors, we are able to build a new predictor that predicts the
series as well as the best predictor in the family, up to a remainder of order
$1/\sqrt{n}$.
We introduce the notion of continuously invertible volatility models that
relies on some Lyapunov condition and some regularity condition. We show that
it is almost equivalent to the ability of the volatilities forecasting using
the parametric inference approach based on the SRE given in [16]. Under very
weak assumptions, we prove the strong consistency and the asymptotic normality
of the parametric inference. Based on this parametric estimation, a natural
strongly consistent forecast of the volatility is given.
Observing a stationary time series, we propose a two-step procedure for the
prediction of the next value of the time series. The first step follows machine
learning theory paradigm and consists in determining a set of possible
predictors as randomized estimators in (possibly numerous) different predictive
models. The second step follows the model selection paradigm and consists in
choosing one predictor with good properties among all the predictors of the
first steps.
This paper is devoted to the off-line multiple change-point detection in a
semiparametric framework. The time series is supposed to belong to a large
class of models including AR($\infty$), ARCH($\infty$), TARCH($\infty$),...
models where the coefficients change at each instant of breaks. The different
unknown parameters (number of changes, change dates and parameters of
successive models) are estimated using a penalized contrast built on
conditional quasi-likelihood.
The aim of this paper is to provide conditions which ensure that the affinely
transformed partial sums of a strictly stationary process converge in
distribution to an in?nite variance stable distribution. Conditions for this
convergence to hold are known in the literature. However, most of these results
are qualitative in the sense that the parameters of the limit distribution are
expressed in terms of some limiting point process.