Template:Cumulative reliability gumpz

Cumulative Reliability

For many kinds of equipment, especially missiles and space systems, only success/failure data (also called discrete or attribute data) is obtained. Conservatively, the cumulative reliability can be used to estimate the trend of reliability growth. The cumulative reliability is given by [3]:

[math]\displaystyle{ \bar{R}(N)=\frac{N-r}{N} }[/math]

where:

[math]\displaystyle{ \begin{align} & N= & \text{ the current number of trials} \\ & r= & \text{ the number of failures} \end{align} }[/math]

It must be emphasized that the instantaneous reliability of the developed equipment is increasing as the test-analyze-fix-and-test process continues. In addition, the instantaneous reliability is higher than the cumulative reliability. Therefore, the reliability growth curve based on the cumulative reliability can be thought of as the lower bound of the true reliability growth curve.