Tc. Haab et Ke. Mcconnell, COUNT DATA MODELS AND THE PROBLEM OF ZEROS IN RECREATION DEMAND ANALYSIS, American journal of agricultural economics, 78(1), 1996, pp. 89-102
In this paper we develop a count data model for consumer demand which
explicitly allows for a large number of zero observations for the depe
ndent variable, and separation of the participation versus quantity de
cisions. The advantages of the model over traditional censored and cou
nt demand models are brought out, and the appropriate consumer surplus
measures are derived. By introducing a random error term into the tra
ditional count model demand function, the appropriate measure of expec
ted consumer surplus for count models is derived. The model is illustr
ated using a recreational survey of the general population.