A Bartlett-type formula is proposed for the asymptotic distribution of the sample autocorrelations ofnonlinear processes. The asymptotic covariances between sample autocorrelations are expressed as thesum of two terms. The first term corresponds to the standard Bartlett’s formula for linear...

We consider linearity testing in a general class of nonlinear time series models of order one, involving a nonnegative nuisance parameter that (a) is not identified under the null hypothesis and (b) gives the linear model when equal to zero. This paper studies the asymptotic distribution of the...

This article is concerned by testing the nullity of coefficients in GARCH models. The problem is nonstandard because the quasi-maximum likelihood estimator is subject to positivity constraints. The paperestablishes the asymptotic null and local alternative distributions of Wald, score, and...

Jensen and Rahbek (2004a) claim that consistency and asymptotic normality hold for the quasi-maximumlikelihood estimator (QMLE) of (!0, 0) in nonstationary ARCH(1) models. In fact their result onlyconcerns a constrained QMLE, in which the intercept is fixed, and under a reinforced...

The main estimation methods of the univariate GARCH models are reviewed. A special attention is givento the asymptotic results and the quasi-maximum likelihood method.Keywords : Asymptotic properties of estimators, Efficient estimation, GARCH model, Quasi MaximumLikelihood Estimation, Weighted...

In order to be consistent with volatility processes, the autoregressiveconditional heteroskedastic (ARCH) models are constrained to havenon-negative coefficients. The estimators incorporating these constraints possessnon standard asymptotic distributions when the true parameter has...

The asymptotic distribution of the QML estimator for GARCH processes, with coefficients possibly equal to zero, is established. This distribution is the projection of a normal vector distribution onto a convex cone. The results are derived under mild conditions which, for important subclasses,...

A class of stochastic unit-root bilinear processes, allowing for GARCH-type effects with asymmetries, is studied. The volatility is not bounded away from zero and is minimum for non zero innovations, which are important differences with the standard GARCH. Necessary and sufficient conditions for...