Belgian Institute for Road Safety, Behaviour and Policy Department, 1405 Chaussée de Haecht, B-1130 Brussels, Belgium.
Accid Anal Prev. 2010 Mar;42(2):645-53. doi: 10.1016/j.aap.2009.10.011. Epub 2009 Nov 7.
This paper aims at addressing the interest and appropriateness of performing accident severity analyses that are limited to fatal accident data. Two methodological issues are specifically discussed, namely the accident-size factors (the number of vehicles in the accident and their level of occupancy) and the comparability of the baseline risk. It is argued that - although these two issues are generally at play in accident severity analyses - their effects on, e.g., the estimation of survival probability, are exacerbated if the analysis is limited to fatal accident data. As a solution, it is recommended to control for these effects by (1) including accident-size indicators in the model, (2) focusing on different sub-groups of road-users while specifying the type of opponent in the model, so as to ensure that comparable baseline risks are worked with. These recommendations are applied in order to investigate risk and protection factors of car occupants involved in fatal accidents using data from a recently set up European Fatal Accident Investigation database (Reed and Morris, 2009). The results confirm that the estimated survival probability is affected by accident-size factors and by type of opponent. The car occupants' survival chances are negatively associated with their own age and that of their vehicle. The survival chances are also lower when seatbelt is not used. Front damage, as compared to other damaged car areas, appears to be associated with increased survival probability, but mostly in the case in which the accident opponent was another car. The interest of further investigating accident-size factors and opponent effects in fatal accidents is discussed.
本文旨在探讨仅使用致命事故数据进行事故严重程度分析的意义和适当性。本文特别讨论了两个方法学问题，即事故规模因素（事故中车辆的数量及其占用率）和基准风险的可比性。本文认为，尽管这两个问题通常在事故严重程度分析中起作用，但如果分析仅限于致命事故数据，则这些因素对生存概率的估计等方面的影响会加剧。为此，建议通过以下两种方法来控制这些影响：（1）在模型中包含事故规模指标；（2）在指定模型中的对手类型时，重点关注不同的道路使用者子群体，以确保使用可比的基准风险。这些建议应用于使用最近建立的欧洲致命事故调查数据库（Reed 和 Morris，2009）中的数据来研究涉及汽车乘客的致命事故的风险和保护因素。结果证实，估计的生存概率受到事故规模因素和对手类型的影响。汽车乘客的生存机会与其自身年龄和车辆年龄呈负相关。不系安全带也会降低生存机会。与其他受损汽车区域相比，前部损坏似乎与更高的生存概率相关，但主要是在事故对手是另一辆车的情况下。本文还讨论了进一步研究致命事故中的事故规模因素和对手影响的意义。
