Score contribution per author:
α: calibrated so average coauthorship-adjusted count equals average raw count
In this study, the double-hurdle model typically used in cross-sectional data is extended to panel data structures. The new double-hurdle model can account not only for the censored nature of commodity purchases, but also for the dynamics of the purchase process. In this model, a flexible error structure is assumed to account for state dependence and household-specific heterogeneity. In the empirical application for milk purchases, it is found that generic advertising increases the probability of market participation as well as the purchase quantity and incidence. Temporal dependence is also found in both purchase and participation equations.