Defining risk

Risk is the focal topic in the management of many activities and technologies. For that management to be successful, an explicit and accepted definition of the term risk is essential. Creation of that definition is a political act, expressing the definers' values regarding the relative importance of different possible adverse consequences for a particular decision. Those values, and with them the definition of risk, can change with changes in the decisionmaker, the technologies considered, or the decision problem. After a review of the sources of controversy in defining risk, a general framework is developed, showing how these value issues can be systematically addressed. As an example, the approach is applied to characterizing the risks of six competing energy technologies, the relative riskeness of which depends upon the particular definition used.