ABSTRACT
Risk managers often want “the number.” What they may not always understand is that we may not know the answer or that the answer can be one of any number of possibilities. Risk managers need to understand the instrumental uncertainty and how it could affect the decisions they must make. This chapter addresses the need for assessors and managers to understand the results of a probabilistic risk assessment. It describes methods for examining the quantities and their probabilities. The look at quantities includes categorical, nonprobability and probability quantities. The five-number summary is presented as a useful presentation for characterizing uncertainty. The look at probabilities emphasizes quantiles, threshold probabilities, confidence statements, tail probabilities and stochastic dominance. Information revealed by relationships found in scatter plots, correlations, re-expression of values and comparisons are considered. All of this is done to answer the risk manager's questions. The promise of data visualization and big data for improving the understanding of risks is considered.
