Template:Grouped data rga: Difference between revisions

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==Grouped Data== <!-- THIS SECTION HEADER IS LINKED FROM: Operational Mission Profile Testing. IF YOU RENAME THE SECTION, YOU MUST UPDATE THE LINK(S). -->
#REDIRECT [[Crow Extended]]
 
Parameter estimation for grouped data is the same as described previously in the [[Crow-AMSAA - NHPP| Crow-AMSAA (NHPP) chapter]]. 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  <math>{{\lambda }_{BD}}</math>  and  <math>{{\beta }_{BD}}</math>  are calculated using the first occurrences of the BD modes such that:
 
 
::<math>\underset{i=1}{\overset{k}{\mathop \sum }}\,{{n}_{i}}\left[ \frac{T_{i}^{\widehat{\beta }}\ln {{T}_{i}}-T_{i-1}^{\widehat{\beta }}\ln {{T}_{i-1}}}{T_{i}^{\widehat{\beta }}-T_{i-1}^{\widehat{\beta }}}-\ln {{T}_{k}} \right]=0</math>
 
 
::<math>\widehat{\lambda }=\frac{n}{T_{k}^{\widehat{\beta }}}</math>
 
 
where  <math>{{n}_{i}}</math>  is the number of distinct BD modes within the  <math>{{i}^{th}}</math>  interval. For test-fix-find-test data, the maximum likelihood estimates of  <math>{{\lambda }_{BC}}</math>  and  <math>{{\beta }_{BC}}</math>  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 are calculated using the same as the procedure presented in Chapter 5. If there are no BC modes, the confidence bounds on the demonstrated failure intensity and MTBF, projected failure intensity and MTBF and growth potential failure intensity and MTBF are the same as the procedure presented in Section 9.5. If there are BC modes, then the confidence bounds on the demonstrated failure intensity and MTBF are the same as the procedure presented in Chapter 5 and the confidence bounds on the projected failure intensity and MTBF and growth potential failure intensity and MTBF are the same as in Section 9.5. The confidence bounds on time are the same as the procedure presented in Chapter 5. 

Latest revision as of 11:31, 23 August 2012

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