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Topic Reliability, Confidence Level Sample Size

Reliability, Confidence Level Sample Size

Home Forums Old Forums General Reliability, Confidence Level Sample Size

This topic contains 1 reply, has 2 voices, and was last updated by Profile photo of Muhammad Anwar Muhammad Anwar 6 years, 3 months ago.

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  • #158454

    Hello,
    I have a hard time in calculating the sample size for attribute test, reliability and confidence level is predetermined and I have to calculate sample size. Someone gave me equation
    Sample size = ln(1-C) / ln (R). and this equation is for C=0 (ie. zero failure) but I don’t know where is equation came from? any idea..
    and I am also looking for equation with number of failure assocaited on the equation above. I found one online calculator http://www.quality-one.com/products/inttools.php this matches with the equation above if failure is taken “0”. Please help me how this is calculated ..where do I find any textbooks …
    Thanks
    Ramesh

    #159668

    The cumulative Binomial Distribution:
    Where:
     – C.L is the Confidence Level for the Test.  This can be thought of as the Probability of more than the Maximum number of allowable failures occurring on Test.
     – “N” is the number of unit on test or Sample Size
     – “r” is the maximum allowable number of failures on test
     – “R” is the reliability of the “System” for the duration of the test

     
    With “no failure”, Cumulative Binomial Distribution equation is given below:
     
    1 – C.L = R^N
     
     
    Solve for N
    N = LN(1 – C.L)/LN(R)
    You can also solve top first equation for 1 failure and so own.
    If you have any other question, please let me know.
    Muhammad Anwar
     

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