When Is Quantitative Analysis of Variability and Uncertainty Required

8 WHEN IS QUANTITATIVE ANALYSIS OF VARIABILITY AND UNCERTAINTY REQUIRED  

The issues considered in the preceding sections imply that variability and uncertainty should be considered in some way in every risk assessment. 

Screening assessments incorporate variability and uncertainty implicitly, by using worst-case assumptions and safety factors. As mentioned earlier, these have rarely been based on a quantitative analysis and may not take account of the full range of uncertainties, so in principle they should be reviewed to determine whether they provide adequate margins of safety. 

In higher tier assessments, the question is not so much whether uncertainty analysis is required, but rather whether it should be quantitative and what methods should be used for it. The previous Pellston workshop made the following recommendations as a general guide (Warren-Hicks and Moore 1998)  

A variety of methods are available for analyzing variability and uncertainty quantitatively. Later chapters describe the main approaches and provide guidance on how to decide which is appropriate for a particular case. 

---