Risk matrices are probably the inter-industry safety standard as the primary tool used in risk evaluation.
Risk matrices are simplistic charts that use ―
1. Probability and
2. Severity to quantify the risk priority of a real or hypothetical safety scenario. The quantification is generally broken into 3 categories:
• Acceptable risk (green);
• Unacceptable risk (red); and
• Acceptable with mitigation, meaning risk may not yet be as low as reasonably possible (yellow).
Some organizations use 1 or 2 additional colors, such as light green and/or orange, though these colours only provide further ―aesthetic and risk granularity rather than general quantification. Risk matrices are ultimately used as risk management tools to rank risks with the risk grid and the calculated risk indices.
The risk matrix is broken into a grid. The grid is usually 5x5, though it can be larger or smaller depending on company needs. The grid is used to assign a calculated ―number to the risk, which is combination of Probability x Severity, and represents the risk priority.
The risk matrix grid: - Usually increases in severity from left (low) to right (high);
-Usually increases in probability from bottom (low) to top (high); but
- A risk matrix can move in any direction, so this matrix grid move from right to left and top to bottom, right to left and bottom to top, or left to right and top to bottom.
