Risk Metrics: Interpretation and Choice

This paper gives an overview of common risk metrics, maps them into a decision context, and suggests a set of evaluation criteria. The motivation is that risk analysis is carried out to inform decision-making, and that the content and perceived legitimacy of information from a risk analysis hinge on the metrics that are used to express the results. A tabular overview of the most common metrics for harm to people, assets, and the environment is given, with emphasis on clarifying their meaning, pros and cons. The metrics are linked to different decision contexts and stakeholder needs, and eleven criteria are established to aid in the choice thereof. Principal issues concerning the adequacy of single as well as sets of risk metrics are finally raised and make the basis for further work.