5.3 __Statistical Distributions Used in
Reliability Models__

There are many standard statistical distributions which may be
used to model the various reliability parameters. It has been found that a
relatively small number of statistical distributions satisfies most needs in
reliability work. The particular distribution used depends upon the nature of
the data, in each case. The following is a short summary of some of the
distributions most commonly used in reliability analysis, criteria for their
use, and examples of application. Figures 5.3-1 and 5.3-2 are summaries of the
shape of common failure density, reliability, and hazard rate functions for
the distributions described. Each distribution will be described in more
detail, with reliability examples, in the following sections.