Utility-maximizing model of household time use for independent, shared, and allocated activities incorporating group decision mechanisms

Existing activity-based models of transport demand typically assume an individual decision-making process. The focus on theories of individual decision making may be partially due to the lack of behaviorally oriented modeling methodologies for group decision making. Therefore, an attempt has been made to develop a new model (called the g-Logit household time-use model) for time-use analysis that incorporates group decision-making mechanisms. To do that, it is proposed that household utility function be defined in the form of multilinear utility function, which can represent interactions among household members and interactions among their activities (four types of activity: in-home, out-of-home independent, allocated, and shared). By introducing this household utility function into the time allocation approach, each member's time-use functions for different types of activities are obtained. The function for independent activities has a structure similar to the one for allocated activities, except the weight parameters are different. In contrast, the time-use function for shared activities has a completely different structure, which results from the complicated processes and strategies for household decision making. The effectiveness of the proposed model is confirmed with activity-travel diary data