On jointly analyzing the physical activity participation levels of individuals in a family unit using a multivariate copula framework

The current paper focuses on analyzing and modeling the physical activity participation levels (in terms of the number of daily “bouts ” or “episodes ” of physical activity during a weekend day) of all members of a family jointly. Essentially, we consider a family as a “cluster ” of individuals whose physical activity propensities may be affected by common household attributes (such as household income and household structure) as well as unobserved family-related factors (such as family life-style and health consciousness, and residential location-related factors). The proposed copula-based clustered ordered-response model structure allows the testing of various dependency forms among the physical activity propensities of individuals of the same household (generated due to the unobserved family-related factors), including non-linear and asymmetric dependency forms. The proposed model system is applied to study physical activity participations of individuals, using data drawn from the 2000 San Francisco Bay Area Household Travel Survey (BATS). A number of individual factors, physical environment factors, and social environment factors are considered in the empirical analysis. The results indicate that reduced vehicle ownership and increased bicycle ownership are important positive determinants o