Repairable systems reliability trend tests and evaluation

Peng Wang, David W. Coit

Research output: Contribution to journalConference articlepeer-review

36 Scopus citations


Repairable systems reliability trend tests are reviewed, extensively tested and compared to evaluate their effectiveness over diverse data patterns. A repairable system is often modeled as a counting failure process. For a counting failure process, successive inter-arrival failure times will tend to become larger (smaller) for an improving (deteriorating) system. During testing and development of new systems, reliability trend analysis is needed to evaluate the progress of the design development and improvement process. Often a program of testing and modification, followed by more testing and modification, is required to achieve a desired system reliability goal. Reliability trend tests can be an important part of this program. The objective of system reliability trend tests is to determine whether and how the pattern of failures is significantly changing with time. This paper reviews the following four trend tests: (1) Crow/AMSAA Test, (2) PCNT (pair-wise comparison nonparametric test), (3) Laplace Test, and (4) Lewis-Robinson Test. These tests are extensively tested, evaluated and compared for diverse repairable system reliability trends. Particular emphasis focused on comparisons with low sample sizes. Simulation models for trend tests are presented and discussed; and simulation results are summarized and compared. Based on these comparisons, it is concluded that the Crow/AMSAA test is the most robust trend test.

Original languageEnglish
Article number11D4
Pages (from-to)416-421
Number of pages6
JournalProceedings - Annual Reliability and Maintainability Symposium
StatePublished - 2005
Externally publishedYes
EventAnnual Reliability and Maintainability Symposium, 2005 Proceedings: The International Symposium on Product Quality and Integrity - Alexandria, VA, United States
Duration: 24 Jan 200527 Jan 2005


  • Homogeneous poisson process
  • Non-homogeneous poisson process
  • Renewal process
  • Repairable system
  • Trend test


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