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Re: Confidence Intervals for Percent Nonconforming

From: Stan Hilliard
Date: 10/14/2005
Time: 6:50:36 PM

Comments

There is a nomograph for determining variables sampling plans by Lloyd Nelson in Journal of Quality Technology Vol 13, No. 4 October 1981. It will determine confidence intervals for fraction nonconforming to an individual specification limit, ISL, based on n, k,

where k=(ISL - Xbar)/S. There is a method described for SD known and unknowm.

The equasions are developed in Quality Control and inductrial Statistics by Acheson J. Duncan. See ch 11 & 12

There is another nomograph in Duncan that was originally published in Industrial Quality Control, November 1949, p24 by Leo J Jacobson.


Last changed: November 20, 2007