In this article a trip frequency model for recreational and shopping
trips is suggested. The data used comes from a Swedish travel habit
survey where the observations of trip frequencies of both types on each
individual are made on the same day. This is likely to introduce a correlation
structure, which is modeled with a conditional approach where
the number of recreational trips are assumed to be made conditional
on the number of shopping trips. A special interest is devoted to the
effect of travel cost on trip frequencies. As a measure of the sensitivity
of cost changes, elasticity of demand is calculated. The precision of
the elasticities are evaluated with simulated confidence intervals.
Statistiska institutionen , 2002.