This appendix summarises some risk analysis and management terminology used in the book. Unless stated otherwise, the terminology is in line with the international guideline ISO (2009a).

1. • aleatory (stochastic) uncertainty: variation of quantities in a population.

2. This definition is not given in the ISO guideline.

3. • epistemic uncertainty: lack of knowledge about unknown quantities.

4. This definition is not given in the ISO guideline.

5. • event: occurrence or change of a particular set of circumstances.

6. • frequency: number of events per unit of time or another reference.

7. Often frequency is also used for the expected number of events per unit of time.

8. • managerial review and judgement: process of summarising, interpreting and deliberating over the results of risk assessments and other assessments, as well as of other relevant issues (not covered by the assessments), in order to make a decision.

9. This definition is not given in the ISO guideline.

10. • probability: either a knowledge-based (subjective) measure of uncertainty of an event conditional on the background knowledge or a relative frequency (chance). If a knowledge-based probability is equal to 0.10, it means that the uncertainty (degree of belief) is the same as randomly drawing a specific ball out of an urn. A relative frequency-interpreted probability (chance) is the fraction of events A occurring when the situation considered can be repeated over and over again infinitely.

11. This definition is not given in the ISO guideline.

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