Relative vs. Absolute Mitigations

Mitigations having a Relative Risk Reduction

Aligned Element is per default configured to calculate the new RPN using so called relative mitigations. This implies that each mitigation probability/severity reduction/visibility enhancement is subtracted from the original hazard/harm in an accumulative manner.

For example: Original Hazard/Harm: Severity=9, Probability=8 => RPN= 98=>72 First Mitigation with probability reduction 2, => new Probability 8-2=6 => NRPN= 96=>54 Second Mitigation with probability reduction 1, => new Probability 8-2-1= 5 => NRPN = 9*5=>45

This means that the NRPN after applying a mitigation is relative to the initial Hazard/Harm RPN. Depending on where the RPN start you can get a different NRPN when applying the same Mitigations.

Mitigations having an Absolute Risk Reduction

Aligned Elements can also be configured to use so called absolute mitigations. This implies that an applied mitigation designates a new probability/severity/visibility to the hazard/harm.

For example: Original Hazard/Harm: Severity=9, Probability=8 => RPN= 98=>72 First applied Mitigation has a new probability 5 => NRPN= 95=>45 Second applied Mitigation has a new probability 6 => NRPN=9*5=>45

Note that the new probability in the first mitigation "overrides" the new probability in the second probability (i.e. Min(6,5)=>5) and that the second mitigation therefore has no additional risk reducing impact. With this convention the NRPN is absolute to the initial RPN after applying mitigations; where relative mitigations are calculated in an accumulative fashion, the absolute mitigations apply a Min/Floor function of the applied mitigations.