Bellcore/Telcordia Prediction Methods

Lambda Predict supports the three methods described in the Bellcore/Telcordia standards for predicting the steady-state failure rate of an item. In the application, you use the Method properties of a block ( or ) to specify which method to use.

• Method I (also known as the Black Box method) uses the generic failure rates defined by the Bellcore/Telcordia standard.
• Method II allows you to supplement Method I with real data that you've obtained from testing.
• Method III allows you to supplement Method I with real data that you've obtained from an identical or similar item operating in the field. In Lambda Predict, this method is broken down into the following cases:
  • Method III (a) indicates that the item in the prediction folio and the fielded item are identical, and are used under the same environmental conditions.
  • Method III (b) indicates that the item in the prediction folio and the fielded item are identical, but are used under different environmental conditions.
  • Method III (c) indicates that the item in the prediction folio and the fielded item are similar, not identical. You will be required to define the failure rate of the fielded item.

If you use Method II or Method III, you have to specify whether the test/field data were collected for the entire assembly (unit) or for the individual component (devices). The application will enable the appropriate Lab Test Data or Field Data properties based on your selection. For example, if you select the "Method II-Unit" option, the Lab Test Data properties will be enabled only for the block, but if you select the "Method II-Devices" option, those properties will be enabled only for the components under the block.

Note: A component that does not belong to a block always uses Method I (i.e., the Lab Test Data and Field Data properties are unavailable).