Data Sources for Evaluation

As both retrospective and prospective evaluation methods are based in many cases on accident data, a short summary concerning possibilities and limitations of accident data as well as other data sources is given in the following. These general findings have effects on the validity of each method discussed below and are not dependent on the specific method used. 

There is a variety of different accident data bases available for evaluation. Two main criteria for categorizing accidents data bases are representativity and level of detail [12,21]. The representativity is directly but not entirely linked to the number of cases available in the data set. Another factor is the representativity of the sampling scheme used. As a consequence, two categories of accident data are in-depth and national (or international) data collections. 

National statistics are regarded as being most representative for their specific country. For example, the German Federal Statistics, provided by the Federal Statistical Office (Statistisches Bundesamt), collects aU police reported traffic accidents connected to driving traffic. That means that police reported accidents involving only 

As a consequence, some restrictions apply when discussing the validity of findings based on in-depth accident data. The restrictions given in the following refer to GIDAS as an example, but can be transferred to other studies with respect to then-internal structure and sampling criteria  

Other biases may be induced by low case numbers as well as other sampling criteria [16]. 

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