Talk:Np-chart

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Mathematics Low‑priority

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Equation should read:

$n*pbar+/-3*sqrt(n*pbar*(1-pbar))$

Thank you, well spotted. (Note that you can sign your posts by placing four tildes.) -- Jayen 466 00:14, 6 February 2008 (UTC)Reply

Text removed

Latest comment: 15 years ago1 comment1 person in discussion

I've removed the following text that had been added by an IP:

Notice that the using the Central limit theorem approximation is wrong in most cases. The chance that a process will have a sample size big enough and a percentage of defects big enough in order to pass the $n*p>5$ approximation test is not very big. In order to calculate Control limits correctly, one must choose an α =1-P(LCL < X_i < UCL/μ=n•p) where X_i = p_i•n and extract the control limits using this formula.

This does not seem to be the mainstream position on how to calculate the control limits; at the very least, it is likely to be contentious and should be backed up by a reliable source. JN 466 23:13, 12 June 2009 (UTC)Reply

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