the interaction between activity choice and duration: application of copula-based and nested-logit models

There is a relationship between choosing an activity and duration of that activity, especially for nonmandatory ones. some previous studies have analyzed the decisions about an activity type and duration independently, though some others have used joint models. this paper contributes to the body of knowledge through using nested-logit and copulabased models for assessing the existence of interdependency or a hierarchy between non-mandatory activity choice and the relative duration. in the nestedlogit model, it is assumed that error terms of these decisions are interrelated, though one is influenced by another. in contrast, the copula-based model can accommodate spatial error correlation across observational units without imposing a restrictive distribution assumption on the dependency structures between the error components. the data from qazvin, a city in iran, are used for estimating both nested-logit and copula-based models and the best variables explaining both choices for each model have been selected. the final models were compared in terms of log-likelihood at convergence and adjusted likelihood ratio index. the results indicated that there are some common influential observed and unobserved factors between these decisions. also, copula-based joint model with ρ_0^2 equals to 0.134 outperforms nestedlogit models and provides a better explanatory power.