The logic of the arrangement
A 5x5 matrix measures a hazard with two questions: how often does this event occur, and how serious is the outcome if it does? Each axis is divided into five steps; the intersecting cell gives the numeric value of the risk. The result falls into a band, and that band says how urgent the control is.
Why it is so common
It takes little time to learn, it can be argued through as a team, and it works even on paper. In a low-hazard workplace it gives enough resolution for most hazards.
Where it falls short
Two axes do not treat exposure duration as a separate variable. A short-lived but very severe hazard and a moderate hazard with constant exposure can land in the same cell. Where duration is decisive, a three-axis method gives a truer result.
Who gives the score
A score is not one person's judgement. The worker who does the job, the safety specialist and, where needed, the workplace physician look at the same hazard separately; diverging scores are discussed and the reasoning is recorded. A score with no recorded reasoning cannot be defended at the next assessment.
In Optifora
The risk assessment module sets the matrix up on screen, collects scores from team members separately, and computes the band and the control priority itself. A control becomes a task and is tracked until it is closed.