Grouped Data Reference Example

This example compares the results for grouped data.

MIL-HDBK -189A, Section 6.3.1.7.5, pg. 162, 2009.

For this example, the following will be calculated:
 * Parameters of the Crow-AMSAA (NHPP) model
 * Demonstrated MTBF (DMTBF)
 * Chi-squared goodness of fit

The following table shows the data.

The book has the following results:


 * Beta = 0.753, Lambda = 1.53


 * DMTBF = 2.6 hours


 * $$\,\!\chi ^{2}$$ = 5.5, critical value = 7.8 (Assume significance level = 0.1. Since $$\,\!\chi ^{2}$$ < critical value can fail to reject hypothesis that the Crow-AMSAA model fits the data).

In RGA, the Crow-AMSAA (NHPP) model with the maximum likelihood estimation (MLE) method was used to calculate the results.


 * The model parameters are:




 * The chi-squared goodness-of-fit test results:




 * Failure intensity vs. time plot: