Risk Assessment, 2nd Edition

Chapter 9 Data for Risk Analysis

9.1 Types of Data

A wide range of information is necessary as input to any risk assessment and in particular the data needs for quantitative risk assessments will be extensive. The required data may be grouped into two broad categories:

• Descriptive data. These types of data describe the study object and the context in which it is placed, covering the technical systems, the organization, the operation, inputs and outputs, and the environmental factors influencing the study object. The descriptive data can be regarded as facts related to the present situation and can normally be established with limited uncertainty, even if the effort to collect the information may delimit how much detail we go into. Before applying the descriptive data in the analysis, we need to make assumptions about the future state of the study object and its operating context and modify the data based on these assumptions. Obviously, this introduces uncertainty in these data when used in risk assessment. Operational data as they are today may well change in the future due to increased or reduced production, and this will have to be reflected in the data sets that are used in the analysis. This information largely has to be provided as part of the operating context but assumptions about the future state may also have to be made by the risk analyst.
• Probabilistic data. These types of data cause most problems for the risk analyst. They are related to how likely it is ...