ABSTRACT
This chapter explores the bases of risk assessment and demonstrates that judgment of risk is fallible. It also shows that the degree of fallibility is often surprisingly great and that faulty estimates may be put forth with much confidence. For almost 40 years, researchers have been using psychometric methods to elicit quantitative measures of perceived risk, perceived benefits, and acceptable levels of risk from a wide variety of activities, technologies, and natural hazards. This "psychometric paradigm" encompasses a theoretical framework that assumes risk is subjectively defined by individuals and may be informed by a wide array of psychological, social, institutional, and cultural factors. There are emerging networks across communities and even larger scales, and, of course, decision and deliberation processes can matter greatly. The field of risk perception and its communication have been continually plagued by two often entirely unmerited assumptions regarding public attitudes to and acceptance of risks.
