ABSTRACT
Uncertainty is a measure of the ‘‘goodness’’ of an estimate, such as performance of a hazard
barrier. Without such a measure, it is impossible to judge how closely the estimated value
relates or represents the reality, and provides a basis for making decisions related to health
and safety risks. Uncertainty arises from lack of or insufficient knowledge about events,
system states, processes, and phenomena that factor into the estimation. Epistemologists have
spent years trying to understand what it means when we say we know something. Despite this,
unfortunately, the literature does not offer a universally acceptable definition of knowledge,
but a working definition of knowledge in the context of risk analysis is ‘‘ . . . a mixture of
experience, values, contextual information, and insight that provides a framework for evalu-
ating and incorporating new experience and information and making rational decisions.’’
Knowledge originates and is applied in the minds of the knower. In human-dominated
organizations, it often becomes embedded both in documents or other repositories and in
organizational routines, processes, practices, and norms. Clearly knowledge is not a simple
element; rather it is mixture of many elements. It is intuitive and therefore hard to capture in
words or understand logically, and unlike other things and properties around human beings,
knowledge is harder to pin down.
