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.
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.