Some Bivariate Probability Models Applicable to Traffic Accidents and Fatalities

Abstract

which may lead to one or more fatalities. It is clear that the number of fatal accidents Y and the number of fatalities Z are both positively correlated with the number of causing accidents X. What is unclear, however, is how sometimes a major accident involving large property damage is not fatal while a minor accident may be fatal. This reflects the uncontrollable nature of those factors which cause traffic fatalities. This suggests that a probability model might be used to express the relationship between the number of accidents and the number of fatal accidents and the relationship between the number of accidents and the number of fatalities. In this investigation, two bivariate probability models will be studied: one for the joint distribution of the number of accidents and the number of fatal accidents; and one for the joint distribution of the number of accidents and the number of fatalities. In both models, the number of accidents X at a certain location during a given time interval is assumed to