Crow Extended Examples

For reliability growth data analysis only.

The Crow Extended model can be used with data obtained from developmental testing or from systems operating in the field. The following topics provide examples of using the model with these different types of data:

• The developmental testing example uses data obtained from a single system during a developmental test. In this scenario, design fixes are applied during the test. Thus, reliability growth is expected to be observed during the test, and additional growth can be projected for fixes that will be applied after the test.
• The operational testing example uses data obtained from two fielded repairable systems that were tested under customer use conditions. In this scenario, any repairs performed during the test are assumed to be minimal repairs (i.e., they do not improve the system reliability). All permanent design fixes are delayed until after the test. Thus, reliability growth is not expected to be observed during the test, but the model will project the growth due to fixes that will be applied after the test.