4.2 Risk Matrix Explanation

[Scene: Instructor (Arya or Liza) stands next to a large display screen showing a blank 5x5 matrix. Calm, focused delivery.]
INSTRUCTOR ( Liza):
Liza - John We’ve talked about hazards—but to manage them, we need to understand risk.
And for that, we use a tool called the Risk Matrix.
It helps us figure out how serious a hazard really is—by asking two questions:
[Visual: Slide appears with two boxes]
1. What’s the probability this will happen?
2. If it does happen, what’s the severity of the outcome?

[Visual: On-screen 5x5 Risk Matrix appears with labeled axes]

Probability / Severity Minimal Possible Probable Likely Imminent
Minor 1 2 3 4 5
Moderate 2 4 6 8 10
Severe 3 6 9 12 15
Major 4 8 12 16 20
Catastrophic 5 10 15 20 25

Liza (pointing to chart): The matrix works like this: John
Risk = Probability × Severity
Let’s look at the scale now John
[Zoom into X-axis: Probability]
Probability — How likely is the hazard to occur?
• Minimal or Nil – Highly unlikely
• Possible – It might happen
• Probable – It’s somewhat likely
• Likely – It’s expected at some point
• Imminent – It’s almost certain
[Zoom into Y-axis: Severity]
Severity — What happens if it does?
• Minor – Small injury, low impact (Category 1 - First Aid case)
• Moderate – Medical treatment, some downtime (Category 2 - MTC)
• Severe – Serious injury or disruption (Category 3 - Restricted Work day case)
• Major – Long-term disability, major damage (Category 4 - LTI or Partial temporary disability )
• Catastrophic – Fatality or total system failure (Category 5 - Fatal / Total Permanent Disability )

[Visual: Risk Matrix heatmap overlay — green to red gradient]
Liza:
When we multiply Probability × Severity, we get a Risk Score.
• 1 to 4: Acceptable to proceed for the work.
• 5 to 25:Need additional control measures to reduce the risk score less than 5.
If the risk score is in between 5 - 25, work authorisation cannot be given by Performing authority and area owners.
[Visual: Example appears — “Working at Height Without Guardrails”]
Example:
• Probability = Likely (4)
• Severity = Major (4)
Risk = 4 × 4 = 16 → High Risk
That means the task must not proceed without additional control measures to mitigate the risk score to acceptable levels.
Liza (closing):
The Risk Matrix helps us stop guessing and start measuring risk.
By using this method, we make better decisions—and safer workplaces.
Let’s move on to how we use HOC to reduce the risk now..

[End Screen: Risk Matrix Summary + “Probability × Severity = Risk”]