Impact of different criteria for identifying intra-household interactions: a case study of household time allocation

Studies of household activity time allocation patterns typically do not differentiate between joint and independent activities. For those that do, more often than not, they use a set of restrictive criteria for identifying joint activities. One consequence of using such criteria is that the occurrence of joint activities may be underestimated due to inconsistent reporting or ambiguities involved in many large-scale, activity-travel surveys. This research is unique in its effort to examine the impacts of criteria at different levels of flexibility (i.e., restrictive vs. flexible) on the identification of joint activities, and the implications of such criteria on our understanding of household time allocation patterns. Using data from the first wave of the Toronto Travel-Activity Panel Survey, the results derived from both the descriptive analysis and structural equation modeling provide evidence of disparity. Specifically, the use of flexible criteria improves model fit, and provides more insights into household time allocation patterns. These findings suggest that new activity-travel surveys should collect information on involved persons. However, in the absence of such companion information, transportation modelers should not necessarily use restrictive criteria to identify joint activities. Instead, they should use more flexible criteria.