Qualitative Methods

The ALARP (As Low as Reasonably Practicable) principle is based on the fundamental thinking of ‘acceptable’ or ‘tolerable’ risks. It allows analysts and decision makers to define boundaries to combine probability-consequence scales. These boundaries can be used to delineate acceptable and intolerable risks. This allows decision makers to evaluate whether a system or process poses certain risks which need to be treated using risk-control options. The ALARP principle can easily be combined with tools such as Risk Matrices to graphically represent the boundaries of risk tolerability.

In a qualitative approach, risks are usually categorized into “high”, “medium” and “low”, and are represented in a risk matrix. This risk matrix represents the possibility and severity in order to integrate the potential accident scenarios that were identified in the threat identification stage. Inside the matrix, the criticality of a risk, through the use of colors, can identified. The results provided by this matrix can be used to compare risks and identify improvement and mitigation measures.

The Delphi method was developed in order to identify possible targets in the USA during the Cold War. The Delphi method was gradually applied in civilian areas and is now frequently used for political and social questions and issues, for the development of science and technology and in the business environment (e.g. marketing, R&D). The Delphi method is a structured group communication process with the aim of answering questions or finding a consensus on facts about which uncertain and incomplete knowledge naturally exists.

The FTA (fault tree analysis) is a scientific method for detailed fault analysis. It serves the systematic identification and documentation of possible causes for errors or misconduct. Found causes are broken down as precisely as possible to get a comprehensive fault analysis.

Checklists are a very simple way to identify risks. As a rule, checklists consist of standardized questionnaires that help to systematically record risks. They can contain open or closed questions, whereby closed questions are better suited for the identification of risk potentials, since the evaluation of the answers is simpler and thus leads faster to concrete results. The questions mostly arise with creative techniques. Workshops, brainstorming, etc. are most commonly used in the creation process.