Eluru Naveen, Bhat Chandra R
The University of Texas at Austin, Department of Civil, Architectural & Environmental Engineering, 1 University Station C1761, Austin, TX 78712-0278, United States.
Accid Anal Prev. 2007 Sep;39(5):1037-49. doi: 10.1016/j.aap.2007.02.001. Epub 2007 Mar 26.
This paper formulates a comprehensive econometric structure that recognizes two important issues in crash-related injury severity analysis. First, the impact of a factor on injury severity may be moderated by various observed and unobserved variables specific to an individual or to a crash. Second, seat belt use is likely to be endogenous to injury severity. That is, it is possible that intrinsically unsafe drivers do not wear seat belts and are the ones likely to be involved in high injury severity crashes because of their unsafe driving habits. The preceding issues are considered in the current research effort through the development of a comprehensive model of seat belt use and injury severity that takes the form of a joint correlated random coefficients binary-ordered response system. To our knowledge, this is the first instance of such a model formulation and application not only in the safety analysis literature, but in the econometrics literature in general. The empirical analysis is based on the 2003 General Estimates System (GES) data base. Several types of variables are considered to explain seat belt use and injury severity levels, including driver characteristics, vehicle characteristics, roadway design attributes, environmental factors, and crash characteristics. The results, in addition to confirming the effects of various explanatory variables, also highlight the importance of (a) considering the moderating effects of unobserved individual/crash-related factors on the determinants of injury severity and (b) seat belt use endogeneity. From a policy standpoint, the results suggest that seat belt non-users, when apprehended in the act, should perhaps be subjected to both a fine (to increase the chances that they wear seat belts) as well as mandatory enrollment in a defensive driving course (to attempt to change their aggressive driving behaviors).
本文构建了一个综合计量经济结构，该结构认识到碰撞相关伤害严重程度分析中的两个重要问题。首先，一个因素对伤害严重程度的影响可能会受到个体或碰撞所特有的各种可观测和不可观测变量的调节。其次，安全带的使用可能与伤害严重程度存在内生性。也就是说，本质上不安全的驾驶员可能不系安全带，并且由于他们不安全的驾驶习惯，他们更有可能卷入高伤害严重程度的碰撞事故。在当前的研究工作中，通过开发一个安全带使用和伤害严重程度的综合模型来考虑上述问题，该模型采用联合相关随机系数二元有序响应系统的形式。据我们所知，这种模型的构建和应用不仅在安全分析文献中，而且在一般计量经济学文献中都是首次出现。实证分析基于2003年综合估计系统（GES）数据库。考虑了几种类型的变量来解释安全带的使用和伤害严重程度水平，包括驾驶员特征、车辆特征、道路设计属性、环境因素和碰撞特征。结果除了证实各种解释变量的影响外，还突出了以下两点的重要性：（a）考虑未观测到的个体/碰撞相关因素对伤害严重程度决定因素的调节作用；（b）安全带使用的内生性。从政策角度来看，结果表明，对于被当场抓获的未系安全带者，或许应同时处以罚款（以增加他们系安全带的可能性）以及强制参加防御性驾驶课程（以试图改变他们激进的驾驶行为）。
