UC Irvine Institute of Transportation Studies

The model developed and estimated empirically concerns of the allocation of time to out-of-home activities and travel. This model has three important characteristics. 

First, the model is multivariate because there are interdependencies among time usages for different activities. The joint distribution of all relevant out-of-home activity times has to be taken into account. Second, travel is treated as a derived demand. The level of travel is the result of the spatial activity behaviour of the individual. Of course, the exact relation between activity performance and travel demand is highly complex. The spatial dispersion and quality of activity locations and the scheduling of activities by individuals are both important elements that need to be studied in order to predict total travel demand from a given activity pattern. Here a much simpler approach is taken. It is assumed that total travel time expenditure over a certain time period (i.e. one week) for an activity is proportional to the total amount of time engaged in that activity.

The third main feature of the model is its longitudinal character. Longitudinal data have a number of advantages over cross-sectional data (see e.g. Hensher, 1985; Davies and Pickles, 1985; Kitamura, 1989; van Wissen and Meurs, 1989). from a statistical point of view it allows the estimation of model· parameters conditional on un-observed stationary characteristics and individual taste variations. From a theoretical point of view longitudinal data are necessary in order to identify and estimate dynamic processes. In this study only the statistical advantages of longitudinal data will be used. 

This paper is organized as follows. In section two an overview is given-of earlier related work on the allocation of time and the travel consequences. In section three the model methodology will be presented. Next, in section four, the data will be described briefly. Section five contains the empirical results of the model estimation. These results are evaluated and some conclusions are drawn in section six.