ABSTRACT
Risks may be classified as falling into at least three classes, in a way similar to that suggested by N. Cohen and Pritchard: Risks for which statistics of identified casualties are available. Risks for which there may be some evidence, but where the connection between suspected cause and injury to any one individual cannot be traced. Experts' best estimates of probabilities of events that have not yet happened. Many examples of substantial risk have an engineering content. Engineers are involved in the design and construction of systems and components or sub-systems that form part of the systems. The output of the hazard identification and the reliability and failure analysis is a compilation of possible failures, each with a quantitative set of parameters that characterize it for purposes of consequence modelling. There are many risks for which it is possible to relate the detriment to any one of a variety of measures of activity rather than to a simple unit of time.
