Abstract

A random coefficient autoregressive process for count data based on a generalized thinning operator is presented. Existence and weak stationarity conditions for these models are established. For the particular case of the (generalized) binomial thinning. it is proved that the necessary and sufficient conditions for weak stationarity are the same as those for continuous-valued AR(I) processes. These kinds of processes are appropriate for modelling non-linear integer-valued time series. They allow for over-dispersion and are appropriate when including covariates. Model parameters estimators are calculated and their properties studied analytically and/or through simulation. (C) 2009 Elsevier B.V. All rights reserved.