Abstract
Methods are described, by the application of which the probabilities of injury to car occupants in collisions of all types may be estimated from data on injury accidents alone, without having to make counts of accidents in which no injury had occurred. To do this, however, the velocity changes have to be known for all vehicles in the sample, so that separate probabilities of injury may be calculated for a number of successive small intervals of velocity change covering the range of velocity change in the accident sample.
Proceeding in this way, sets of curves of probability of injury at various levels of injury versus velocity change may be drawn, both for overall injury, and for injury to different regions of the body. A sample calculation at one value of velocity change is given.
The method is applicable to single vehicle accidents as well as to collisions, provided that there are at least two car occupants.
It is anticipated that the method will be particularly valuable when applied to estimate the effectiveness of seat belts, since it will then be possible to examine how the protection given changes with severity of accident, thus pointing to where improvements are desirable.
Difficulties which arise when certain analyses of injury accidents are made without introducing probability theory are discussed.
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