Importance measure

[Danylo Malyuta]

Hello SCRAM community,

Different importance measured exist: Birnbaum, DIF, CIF, RAW, RRW, etc. However, these all are dependent on time t - in particular, the mission time. So, if I analyze the fault tree for a mission time of 1 month, I might get different importance measures for the basic events than if I did the analysis for a mission time of 1 year.

While I understand that inherently the importance measures *do* depend on time (example: a safety controller protecting against the failure of an unreliable component becomes more important with time due to the higher chance of the component failing), is there an importance measure that exists which is time-independent (i.e. somehow "global" in scope)?

Kind regards,

Danylo Malyuta.