THE ASYMMETRY OF THE CHANGE IN HOUSEHOLD CAR OWNERSHIP AND UTILIZATION: A PANEL ANALYSIS . TRAVEL BEHAVIOR RESEARCH. 5TH INTERNATIONAL CONFERENCE ON TRAVEL BEHAVIOR

This paper presents a study of household car ownership and use, which emphasises the dynamic interaction between household attributes and car ownership and use. The study aims to examine the competing hypotheses that car ownership: (1) can be represented by a static relationship obtainable by from cross sectional observation; (2) is a function of changes in contributing factors as well as the absolute values of those factors. The second hypothesis has one variant assuming that the changes in contributing factors have symmetric effects and another variant assuming asymmetric effects. Using three types of car ownership models, the analysis offered evidence that factors influencing car ownership have asymmetric effects, and that car ownership behaviour cannot be explained by contemporaneous effects alone. The values of contributing factors in previous periods are at least as important as their values observed concurrently with the behaviour. This can be interpreted as an indication of response lags in car ownership behaviour, and suggests that car ownership reflects the household's long-term considerations rather than short-term responses to changes. In addition, the analysis has shown that car use is also asymmetric, but responds more spontaneously than car ownership to changes in household attributes. (TRRL)