Reliability predictions should be carried out at all stages during the development of a project. By being continuously updated as the design progresses, reliability predictions can indicate whether the design reliability criteria are being met and also whether any elements that detract from the inherent reliability of the product have been eliminated.

The accuracy of reliability predictions depends largely upon the availability of detailed design and operating data. This information may not be available early in a design. However, the requirement for prediction must be used to force detailed information to be made available as early as possible, particularly in critical areas, so that a more thorough and realistic pre-design assessment can be produced. Predictions must therefore be an integral part of the design process from start to finish and not simply a parallel activity.