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The determination of the UCSR ratings is based on a number of assumptions and warrant a number of qualifications. These are listed below.
Assumptions
It has been assumed that:
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TAC claims records and, Victoria, NSW, Western Australian and Queensland Police crash reports accurately recorded driver injury, hospitalisation and death.
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There was no bias in the merging of TAC claims and Victorian Police crash reports related to the model of car and factors affecting the severity of the crash.
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Crashed vehicle registration numbers were recorded accurately on Police crash reports and that they correctly identified the crashed vehicles in the Victorian, NSW and Queensland vehicle registers.
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The adjustments for driver sex, age, speed zone, the number of vehicles involved and the state and year in which the crash occurred removed the influences of the other main factors available in the data that affected crash severity and injury susceptibility.
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The form of the mathematical logistic models used to relate injury risk and injury severity with the available factors influencing these outcomes (including the car models) was correct.
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Information contained in the Police crash records allowed accurate matching of both vehicles involved in crashes between two passenger cars for the purpose of calculating aggressivity ratings.
Qualifications
The results and conclusions warrant at least the following qualifications:
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Only driver crash involvements and injuries have been considered. Passengers occupying the same model cars may have had different injury outcomes.
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Some models with the same name through the 1982 - 2002 years of manufacture may have varied substantially in their construction and mass. Although there should be few such models in these updated results, the rating score calculated for these models may give a misleading impression and should be interpreted with caution.
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Other factors not collected in the data (eg crash speed) may differ between the models and may affect the results. However, earlier analysis has suggested that the different rating scores are predominantly due to vehicle factors alone.
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