5Comparing Predicted and Realized Reliability with Requirements


Once reliability requirements have been established and a system has been developed and deployed, important information can be gained from determining whether the requirements are being met. This chapter will provide you with some ideas and tools you can use to do this. The presentation keys on the two types of reliability requirements introduced in Chapter 2: those based on reliability effectiveness criteria and those based on reliability figures of merit. We offer some statistical procedures appropriate to each case and discuss how to interpret the results they lead to. The chapter closes with some ideas for a failure reporting analysis and corrective action system (FRACAS) that systematizes the process of data collection, archiving, and analysis for more effective and efficient feedback about the reliability of deployed systems.


Systems engineers can get vital feedback about the reliability experienced by customers of their products and services from appropriate collection and analysis of relevant reliability data. This feedback supports important learning about the degree to which realized reliability of the system conforms to its requirements. Any gaps identified are opportunities for improvement of:

  • the process of creating reliability requirements,
  • the design for reliability process, and
  • the reliability modeling process.

The generally accepted way to ...

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