本文主要以探討機車對汽車責任險所可能產生的負外部性影響，以機車密度作為指標，從台灣各個行政區機車分佈密度與交通事故發生機率之關聯性進行研究，配合目前所使用的人、車特性之外的其他風險因素，重新探討現行汽車保險計算保險費率之合理性。另一方面，針對目前機車保險費率偏低之狀況，是否需重新考慮因其產生負外部性、可能導致產險業保險成本增加之特質，進而作為未來機車保險費率計算的考慮因素之一。研究結果證明，機車對汽車第三人責任保險出險具有顯著的負外部性，這個發現，期能成為未來產險公司計算第三人責任險費率考量之新風險分類因子。 The article elaborates the externality of motorcycles on the risk of automobile liability insurance, probing into the risk factors of automobile third party liability insurance by adopting locomotive density as its main negative factor of externalities. The article also examines the reasonability of current insurance rate on automobile insurance, applying some risk factors other than the characteristics of human or vehicle. On one hand, the article studies the relationship between the density of locomotive distribution and the incidence of traffic accidents in each administrative area in Taiwan. On the other hand, considering the low insurance rate in the automobile insurance market, it further discusses if the externalities may burden the P&C insurance industry with high insurance cost and should be considered for insurance rate calculation. Moreover, with the state-of-the-art technology, PAYD(pay-as-your-drive), the risk factor of externalities could be applied to the future rate system of automobile third party liability, making the insurance rate more fair and reasonable. By means of sample observation, assumption establishment, and the empirical research of regression model, the study concludes that there is relationship between the externalities which is locomotive density and the probability of claims on automobile third party liability. Hope the externalities could be applied as a new risk factor to calculate the insurance rate of automobile third party liability insurance in the P&C insurance industry.
