Investigating the Role of Social Networks in Start Time and Duration of Activities

In the context of improving understanding and modeling the capabilities of activity-scheduling processes in travel behavior, this paper explores the role of social networks in the start time and the duration of social activities. The study was performed with a trivariate joint econometric model that was capable of capturing the correlation between unobserved influential factors causing the endogeneity of these three key decisions. The model captures the relevance not only of sociodemographic variables but also of the social network dimension for travelers, or the with whom variable, that is, individuals with whom travelers perform social activities. A particularly relevant case is the role of travel time to social activities, which has a positive effect on longer durations and late start times and which acts as a link between these two basic dimensions (start time and duration) of activity scheduling. The results confirm the relevance of the social context in an episode's temporal characteristics and illustrate aspects that future activity-based travel demand models should incorporate to be able to capture the socializing side of mobility decisions.