What you have a right to expect is the result of the reliability characteristics that were designed and built-in to your systems and equipment, and have been preserved through proper operation and maintenance. If you are able to recognize the things that cause failures, you will be able to make a realistic evaluation of what you have a rright to expect because you can determine the amount of failure prevention that has already been applied. You will also have a head start on achieving the level of performance you desire.

Tip excerpted from Reliability Assessment: A Guide To Aligning Expectations, Practices and Performance by Dan T. Daley