Grouped Data for the Crow Extended Model

Parameter estimation for Grouped data using the Crow-AMSAA model is the same as described in the Grouped Data for the Crow-AMSAA Model section of this on-line reference. The equations used to estimate the parameters of the Crow Extended model are presented next. For test-find-test data, the maximum likelihood estimates of and are calculated using the first occurrences of the BD modes such that:

where ni is the number of distinct BD modes within the ith interval. For test-fix-find-test data, the ML estimates of and are estimated in the same manner using the first occurrences of the BC modes.

Confidence Bounds

The confidence bounds on the parameters for the Crow Extended model for Grouped data is the same as the procedure presented in the Grouped Data Confidence Bounds for the Crow-AMSAA Model section of this on-line reference. If there are no BC modes, the confidence bounds on the demonstrated failure intensity (MTBF), projected failure intensity (MTBF) and growth potential failure intensity (MTBF) are the same as the procedure presented in the Confidence Bounds for the Crow Extended Model section of this on-line reference. If there are BC modes, then the confidence bounds on the demonstrated failure intensity (MTBF) are the same as the procedure presented in the Grouped Data Confidence Bounds on MTBF for the Crow-AMSAA Model section of this on-line reference and the confidence bounds on the projected failure intensity (MTBF) and growth potential failure intensity (MTBF) are the same as in the Confidence Bounds for the Crow Extended Model section of this on-line reference. The confidence bounds on time are the same as the procedure presented in the Grouped Data Confidence Bounds for the Crow-AMSAA Model section of this on-line reference.