ITEM TOOLKIT

192 ITEM ToolKit Getting Started Guide
F-Vesely
The F-Vesely (Fussell-Vesely) importance measure represents an event’s contribution to the system unavailability.
Increasing or decreasing the availability of events with a higher importance value will have the most significant effect on
system availability.
Birnbaum
The Birnbaum measure for an event represents the sensitivity of system unavailability with respect to changes in the events
unavailability.
B-Proschan
The B-Proschan (Barlow-Proschan) event importance measure takes into consideration the sequence of event failures within
its calculation. It is the probability that the system fails because a critical cut set containing the event fails, taking into
consideration that the event fails last.
How to Display a Critical Path
1. Select the Analysis pull-down menu and click on Critical Path. The Critical Path window displays:
2. From this window you can select the Critical Path importance level you wish to use, add and delete levels, check all
levels, uncheck all levels, and use the color palette to assign a color to a specific level.