Method II, also referred to as the black box or parts count method integrated with laboratory data, is used when laboratory or test data is known and is to taken into account during failure rate calculations. It modifies the results for steady state failure rates based on a weighted average for the test data. When tests are very informative, failure rate predictions are heavily influenced by the test data. When tests are less informative, failure rate predictions may be only slightly influenced by the test data.

The various scenarios available with Method II calculations are Case L1, Case L2, Case L3, and Case L4. The following table describes these scenarios.