Statistical Aspects of Injury Severity Part II: The Case of Several Populations but Only Three Grades of Injury

Those types of accident in which a high proportion of casualties are killed are usually those in which also a high proportion are seriously injured. This paper is concerned with the quantification of this correlation. In particular, it was found (using British data) that the variation in injury severity in a number of situations can be described by alterations in the exponent of an exponential distribution of severity, with the boundary between slight and serious injury occurring at one-third the distance from the origin of the boundary between serious and fatal injury.