Deriving a frequentist conservative confidence bound for probability of failure per demand for systems with different operational and test profiles. (February 2017)

• Record Type: Journal Article
• Authors: Bishop, Peter; Povyakalo, Andrey
• Is Part Of: Reliability engineering & system safety. Volume 158(2017)
• Page Start: 246
• Page End: 253
• Publication Date: 2017-02
• Subjects: Statistical testing -- Confidence bounds -- Operational profile -- Software reliability; Reliability (Engineering) -- Periodicals; System safety -- Periodicals; Industrial safety -- Periodicals; Fiabilité -- Périodiques; Sécurité des systèmes -- Périodiques; Sécurité du travail -- Périodiques; 620.00452
• DOI: 10.1016/j.ress.2016.08.019
• Languages: English
• ISSNs: 0951-8320

Abstract

Abstract: Reliability testing is typically used in demand-based systems (such as protection systems) to derive a confidence bound for a specific operational profile. To be realistic, the number of tests for each class of demand should be proportional to the demand frequency of the class. In practice, however, the actual operational profile may differ from that used during testing. This paper provides a means for estimating the confidence bound when the test profile differs from the profile used in actual operation. Based on this analysis the paper examines what bound can be claimed for different types of profile uncertainty and options for dealing with this uncertainty. We also show that the same conservative bound estimation equations can be applied to cases where different measures of software test coverage and operational profile are used. Abstract : Highlights: Calculation of a new confidence bound when the operational profile changes. The bound formula is an analytic approximation that is always conservative. Formula can be used to optimise testing to allow for profile uncertainty. Formulated for demand based systems with different demand classes. But formulae can be generalised (e.g. to continuous time systems).