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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Posted by: Johnson Wood ( )
Organization:Huawei Tech.Ltd.,Co.
Date posted: Tue Aug 14 3:55:01 US/Eastern 2001
Subject: Weibull
The circuit boards burn-in datas are recorded per month, judy as follows: Date Sample Size #Failed 2001-2 1494 34 2001-4 3494 144 2001-5 25902 702 2001-6 20082 682 Which method of Weibull is suitable for this type of data?

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Subject: Infant Mortality / Weibull
Reply Posted by: Joe Dzekevich
Date Posted: Thu Aug 16 9:33:47 US/Eastern 2001
OK...I see now. You want to build-up a distribution and/or histogram of the infant mortality distribution. Break your 24 hours up into multiple time periods, let us say three 8 hour shifts, and collect your data. Write down how many boards are running and how many are up at the end of each 8 hour period. Analyze the data as "inspection" or "interval" data. Treat a runing board as "censored" and a failed board as "failed" and use the time at the end of each inspection period (8, 16, 24 hours). You may also wish to do a special extended test. Run the burn-in for multiple days, taking data on each 8 hour shift. I can de dangerous to extrapolate the data too far into the future, so a multiple day run may help you there. Do this for eacl burn-in lot, and you will construct multiple Weibull distributions. Joe

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