A hazard-based duration model of shopping activity with nonparametric baseline specification and nonparametric control for unobserved heterogeneity
Abstract
Activity duration is an important component of the activity participation behavior of
individuals, and therefore, an important determinant of individual travel behavior. In this paper,
we examine the factors affecting shopping activity duration during the return home from work
and develop a comprehensive methodological framework to estimate a stochastic hazard-based
duration model from grouped (interval-level) failure data. The framework accommodates a
nonparametric baseline hazard distribution and allows for nonparametric control of unobserved
heterogeneity, while incorporating the effects of covariates. The framework also facilitates
statistical testing of alternative parametric assumptions on the baseline hazard distribution and on
the unobserved heterogeneity distribution. Our empirical results indicate significant effects of
unobserved heterogeneity on shopping activity duration of individuals. Further, we find that
parametric forms for the baseline hazard and unobserved heterogeneity distributions are
inadequate, and are likely to lead to substantial biases in covariate effects and hazard dynamics.
The empirical results also provide insights into the determinants of shopping activity duration
during the commute trip.
Description
At the time of publication C.R. Bhat was at the University of Massachusetts at Amherst.