ABSTRACT
Probability is the language of uncertainty and risk = consequence x probability. Anyone involved in risk management, risk assessment, or risk communication will be better prepared the more they understand about probability. Bayesian and frequentist probability schools of thought are contrasted before settling on a pragmatic approach to probability in risk assessment. Essential language and concepts of probability are reviewed before the axioms, propositions, and rules of probability are reviewed. The focus is general with attention given to marginal probability, complementarity, addition rules, multiplication rules, conditional probability, and Bayes Theorem. The use of these concepts is demonstrated in a simple event tree to demonstrate their fundamental value to risk assessment.
