Masashi Kuwano

Dynamic Discrete Choice Model for Multiple Social Interactions

A dynamic discrete choice model for multiple social interactions was developed on the basis of retrospective panel data in the context of household vehicle-type choice. “Social interactions” refer to the influence of reference groups on household choice behavior. However, most studies in transportation have considered a household as a decision maker independent from the society to which it belongs. Social interactions have therefore not been well represented, especially if there were two or more types of reference groups, which may further vary over time. The model was built within the dynamic generalized extreme value framework, which included a set of dynamic elements, such as initial conditions, state dependence, and future expectation. This study defined three types of social interactions: diffusion rates of a vehicle type at the national level and at the neighborhood level and diffusion rate of households with the same income level. A survey was conducted in local Japanese cities in 2006. The survey focused on household vehicle ownership behavior over the 10 years from 1997 to 2006. Model estimation results confirmed that social interactions from reference groups of neighborhoods and households with the same income level were especially influential in decisions about household vehicle-type choice. On the contrary, social interaction from the whole society did not significantly influence the household choice. It was further found that effects of dynamic elements on the household choice were statistically significant.

The Car-Dependent Life

This chapter focuses on car dependence in people’s life. The authors first describe a new phenomenon about the decline in young people’s car ownership and usage by providing additional facts and insights based on literature review and a case study in Japan. Especially, the case study in Japan uses data from a longitudinal national household expenditure survey and confirmed that car ownership and usage decisions in Japan are more or less associated with decisions about other household expenditures. Second, recent research on shared mobility is reviewed from the perspective of smart use of cars. Third, existing studies on cars from the life-oriented consideration are described by looking at shopping behavior (both store-shopping and online shopping) and general purchasing behavior as well as electric vehicle ownership and usage. As for electric vehicles, the influence of lifestyle is explored. Fourth, car ownership and usage for an inclusive society are discussed, where low-income persons, children, and the elderly are focused on. Fifth, behavioral changes toward less dependence on car from a long-term perspective are illustrated. Finally, discussions on car dependence from the life-oriented perspective are given.

Taxation Policies for Promoting Fuel-Efficient Vehicle Ownership and Use

This study evaluates the effects of taxation policies on promoting fuel-efficient vehicle ownership and use. Ownership is described as choice of vehicle type based on a paired combination logit (PCL) model and use is represented by a copula-based multivariate survival (CMS) model that includes both holding duration and annual distance traveled. To estimate the integrated model, the PCL model is first estimated and then incorporated into the CMS model. Policy effects are evaluated by calculating changes in CO2 emissions under different taxation policies. An empirical analysis was conducted of data from a questionnaire survey in the Chugoku region of Japan in 2006. Through the simulation analysis of vehicle-related taxes, it is found that increasing the fuel tax is the most effective means of reducing CO2 emissions, followed by the auto tax and weight tax collected at vehicle inspections. Moreover, it is further observed that, contrary to our expectation, increasing the acquisition tax actually leads to an increase in CO2 emissions.