ABSTRACT
The occurrence of accidents follows basic laws of statistics similar to events such as telephone calls to a home, customers arriving at a department store, or to radioactive decay. It is a commonly accepted assumption in health, safety, and environment (HSE) management that accident frequency is a measure of the HSE performance of the company. This chapter focuses on how people can use basic statistical theory in evaluating data on the occurrence of accidents. It reviews the most important characteristics of statistical theory of Poisson distributions. The characteristic is the frequency functions for the number of events during time periods that are not overlapping are independent stochastic variables. The average number of accidents per period is our best estimate of the underlying or 'true' value of the accident intensity at a company. The 95" confidence interval of such an estimate can easily be calculated.
