We consider a parametric model for time series of counts by constructing a
likelihood-based generalization of a model considered by Zeger (1988). We c
onsider a Bayesian approach and propose a class of informative prior distri
butions for the model parameters that are useful for variable subset select
ion. The prior specification is motivated from the notion of the existence
of data from similar previous studies, called historical data, which is the
n quantified in a prior distribution for the current study. We derive theor
etical and computational properties of the proposed priors and develop nove
l methods for computing posterior model probabilities. To compute the poste
rior model probabilities, me show that only posterior samples from the full
model are needed to estimate the posterior probabilities for all of the po
ssible subset models. We demonstrate our methodology with a simulated and a
real data set.