A Competing Risks Duration Model of Household Vehicle Transactions with Indicators of Changes in Explanatory Variables

A household vehicle transactions model has been developed as a competing risks duration model in this study. The model is developed assuming the following three types of competing risks: replacing one of the vehicles in the household fleet, disposing of one vehicle in the fleet, and acquiring one vehicle to add to the fleet. In addition to the attributes of household, changes in household attributes are expected to have strong effects on vehicle transactions behavior. To account for their effects, dummy variables indicating the occurrence of a change in selected household attributes are defined as time varying covariates and introduced into the model. In addition, vehicle transactions themselves change the needs and motivations for vehicles holding, affecting the timing and the type of the transaction that immediately follows. Dummy variables indicating the type of the preceding transaction are also introduced as time varying covariates into the model. The results of the empirical analysis using a data set collected in a panel survey empirically support the theoretical considerations underlying the model development, and indicate that the effects of changes in household attributes and that of a preceding transaction are well represented in the model. Yamamoto, Kitamura and Kimura 2