Qualitative Risk Analysis
The main steps of a qualitative risk analysis are the same as for a quantitative risk analysis. A qualitative risk analysis method is selected when failure date and statistics are scarce or lacking. The qualitative risk analysis gives insight into single accidents and the consequences of these. The qualitative risk analysis is normally carried as a work session with personnel with in depth knowledge of the system/operation.
The assessment of probabilities and consequences are done based on the system/operational knowledge of the work session participants. The results of the analysis are normally compared with risk acceptance criteria expressed as a risk matrix
A typical risk matrix is shown in the figure below and expresses combinations of accident probabilities and consequences that are:
- Unacceptable (red area)
- Acceptable, but risk reduction measures needs to be considered in an ALARP context (yellow area)
- Unconditionally acceptable ie the risk is negligible (green area)
The qualitative risk analysis method is an efficient tool for identification of main risk contributors and for allocation of the most cost effective risk reduction measures.