Likelihood score |
Descriptor |
FrequencyHow often might it/does it happen |
1 | Rare | This will probably never happen/recur |
2 | Unlikely | Do not expect it to happen/recur but it is possible it may do so |
3 | Possible | Might happen or recur occasionally |
4 | Likely | Will probably happen/recur, but is not a persisting issue/circumstances |
5 | Almost certain | Will undoubtedly happen/recur, possibly frequently |
Probability |
Uncertainty Statement |
Evaluation |
> 80% | Almost certainly | 5 |
61-80% | Probable | 4 |
41-60% | Improbable | 3 |
21-40% | Unlikely | 2 |
1-20% | Highly unlikely | 1 |
Likelihood |
Quantification |
Probability |
Description |
Almost certain | 0 – 12 months | 95% – 100% | The event is expected to occur |
Likely | 1 – 3 years | 65% – 95% | The event will probably occur |
Possible | 3 – 6 years | 35% – 65% | The event might occur at some time |
Unlikely | 6 – 10 years | 5% – 35% | The event could occur at some time but is improbable |
Rare | Beyond 10 years | < 5% | The event may occur only in exceptional circumstances |
These descriptors, whilst standard across the industry, have not sat well for some time. That was until recently when it hit me like the proverbial ton of bricks. It makes absolutely no sense to assess the likelihood of events that are not time or frequency dependent using time or frequency as the measure.
Paladin started to ask – is this an appropriate measure to determine the likelihood of risks such of these?
- Contaminated food served to restaurant patrons
- Worker exposed to unbonded/friable asbestos
- Wrong medication administered to a patient
- Explosion at fuel storage depot
- Legionnaires outbreak in the hospital
- Unauthorised release of, or alteration to client confidential information
Read the full article online here.
So how likely is likely? Understand the effectiveness of your controls to truly understand how likely it is that the risk will materialise as an issue.