In every decision context there are things we know and things we do not know. Risk analysis uses science and the best available evidence to assess what we know—and it is intentional in the way it addresses the importance of the things we don’t know. Primer on Risk Analysis: Decision Making Under Uncertainty lays out the tasks of risk analysis in a straightforward, conceptual manner that is consistent with the risk models of all communities of practice. This primer tackles the question, "what is risk analysis?" Distilling the common principles of the many risk tribes and dialects into serviceable definitions and narratives, it provides a foundation for the practice of risk analysis and decision making under uncertainty for professionals from all walks of life. Readers learn the language, models, and concepts of risk analysis and its three component tasks—risk management, assessment, and communication. Making a distinction between knowledge uncertainty and natural variability, the book also introduces a down-to-earth approach to decision making under uncertainty. Extensive examples illustrate the applicability of the risk analysis principles. The book’s simple and straightforward style—based on the author’s decades of experience as a risk analyst, trainer, and educator—strips away the mysterious aura that often accompanies risk analysis. It describes the principles of risk analysis in a manner that enables readers to better understand and use the models and practice of their individual fields, and to gain access to the rich and sophisticated professional literature on risk analysis. A companion volume, Principles of Risk Analysis: Decision Making Under Uncertainty, supplies the tools, techniques, and methodologies to help readers apply the principles of risk analysis—the "how to." Additional exercises, as well as a free student version of the Palisade Corporation DecisionTools® Suite software and files used in the preparation of this book are available for download.