Downloaded from https://www.everyspec.com AMCP 706-198 ExamDle No,_. Suppose that your prior dsgree-uf-belief about a failure rate is that it is oquiva- lent to having found 4 failures in 2000 hr of testing (Aj a 1/2000-hr). Suppose the test results are 3 failures in 1000 hr. What it your new degree-of-belief? Assume that the conjugate distribution applies. Prooeduro Exampl e 1. State your prior degree-of-belief. 1. r 4, T 2 2000 hr. 2. Find the equivalent failure rate and 2. OS, = 4/2000-hr its uncertainty. See par. 2-12 for formuas -2/1000-hr formula s. coeff, of variation - i/Z = 50%. 3. Find the failure rate and its un- a. A#,tat = 3/1000-hr certainty, for the test results only. coeff.
of variation - i/v'" - 58%. 4. Combine the prior and test results, 4. t,W ( 3 + 4)/(1000 hr + 2000 hr) per conjugate distribution theory. 2.3/1000-hr. coeff. of variation - 1/V'T.4 38%. The prior and after-test results agree reasonably well. Before using this procedure, be sure to siituuate possible test outconies extensively. Example No. 31 shows what can happen. iti. U.