Demonstration Reliability Test Formula with allowance for 'x' Failures

  • Thread starter Disenchanted9000
  • Start date
D

Disenchanted9000

#1
Hi all,

I am in search of a formula that will provide the number of test units required to demonstrate a reliability figure with allowance for 'x' failures.

I know of this formula which allows for zero failures:

N=(ln(1-confidence)/ln(R)), where N is the number of units (round up this answer), R is the reliability from 0-1. Confidence level is also 0-1. Straight forward.

Then, I found this formula which is confusing and also solves for confidence.

______________f_____n!
(1-confidence)= Σ ----------- x (1-R)^i x R^(n-i)
_____________i=0_ i! x (n-i)!

Yikes! Brain hurting....

Need a similar formula to solve for number of units.

Thanks. Robert
 
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D

Disenchanted9000

#6
Thanks v9991. I think the link to "src.alionscience.com/toolbox/oneshotcalc" is what I was looking for. Will try in Excel.
 
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