NASS data are critical to understanding real-world motor vehicle crash performance and the injury risk as a function of crash severity. Data are obtained for comparison of these risks from assessment of the damage to crash involved motor vehicles, assessment of the performance of motor vehicle occupant safety devices, and documentation of injuries sustained by crash victims. Police reported crashes are sampled according to a complex algorithm to produce nationally representative crash data. NASS data have been electronically coded in computerized data files for statistical analysis since 1979. NASS CDS has investigated and collected detailed data on a representative, random sample of more than 119,000 minor, serious, and fatal crashes.
Custom software incorporating aut sample omated quality control is used for data entry.
Separate contractors perform extensive quality control reviews of field case sampling procedures and non-automated data such as scene diagrams and vehicle damage sketches. Additional case data, such as vehicle photographs and scene diagrams, are retained for detailed analysis by the agency and the highway safety community. Contractor staff are trained in NASS investigation procedures at the Transportation Safety Institute in Oklahoma City, Oklahoma. Performance of contractor staff is carefully monitored against defined goals to assure accuracy and completeness of crash sampling and data collection. Police reports used as the source for GES data are collected by CDS teams adjacent to GES sites or by part-time contractor personnel at remote GES sites.