Background: In attempting to achieve high reliability for a system, a basic problem of the
system analysts is how to evaluate the relative component importance. Importance measures are used to
evaluate the component contribution to system reliability. The patents related to importance measures
and their applications in system reliability have been studied. Contents of most patents are related to
system identification, component ranks, reliability improvement, and classification.
Methods: In this paper, some importance measures, such as the improvement potential, Birnbaum importance
and Fussell-Vesely importance, are analyzed to identify the most important component for system
Results: The related properties of importance measures are derived. The change of system reliability is
obtained by improving the component reliability in terms of importance measures.
Conclusion: In order to identify the most important component, and get the maximal system reliability
improvement, the proposed method is a useful guide to determine which component should be managed.