Short answer, there is no such thing as a perfect risk matrix. But there are some fundamental cornerstones to consider when defining a risk matrix. First of all, make sure your risk matrix offers a tolerable risk level on both axes (blue boxes in the example below). This is very important for your follow-up risk estimation & risk evaluation.
Next item; how many levels should I choose for my two risk parameters? In general; the fewer the better, or only as many as needed. On Severity of Consequence, think of the outcome of such an injury, for example, Minor = can be handled by first aid, Severe = requires medical treatment but the injury is reversible, Catastrophic = only irreversible injury and death. On Probability of Occurrence, stay qualitative vs going quantitative, meaning don’t be too specific in your timing. For example Low = Hazardous Event likely to occur several times in the system life cycle.
Last point; What is the benefit of having three risk levels vs only tolerable and intolerable? Having an additional third risk level (e.g. called undesirable) can be very helpful when accepting certain Risk Reduction Measures (RRM). For example that a single RRM of type admin is not allowed to reduce the initial risk of intolerable all the way to a tolerable risk level.
ADVANTIS lets you fully customize your own risk matrix to match your individual needs. We are happy to assist you in setting up your own risk matrix.
Best regards,
ADVANTIS Team
