Predecessor analysis provides for factoring in the field failure rate experience of a predecessor product to better predict the reliability of a “new” product. Performing predecessor analysis is advantageous because a new product (system or assembly) is likely to be more evolutionary than revolutionary. Factoring in the field failure rate experience of the predecessor product allows you to better predict the reliability of the new product.

Predecessor analysis uses the observed field failure rate for the predecessor product and the ratio of the predicted failure rates for the new and predecessor products to estimate a combined failure rate (FR) for the new product. The equation is:

New Product Combined FR = Predecessor Field FR * New Product Predicted FR / Predecessor Predicted FR

Where:

Predecessor Field FR = Observed Number of Failures / Cumulative Calendar Hours

The New Product Predicted FR/Predecessor Predicted FR ratio accounts for differences in application environment, complexity, stresses, and more.