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Confidence Intervals for Percent Nonconforming

From: Richard Weed, Consultant
Date: 10/14/2005
Time: 6:25:05 PM

Comments

Would anyone happen to be familiar with a method to calculate confidence intervals for percent nonconforming estimates obtained by standard variables procedures, Q = (XBAR - L) / S, etc.? Or be able to steer me to an appropriate textbook, paper, or other source? I thought I had a suitable method I found in a paper entitled "Confidence Intervals for the Percent Nonconforming Based on Variables Data" in the October, 1982 issue of the Journal of Quality Technology, published by ASQC. However, based on fairly extensive testing with computer simulation, I'm finding the frequency with which the true value is included within the computed intervals to be quite erratic. I have checked my computer code, and will make further independent tests, but in the meantime I am looking for another source. Any advice anyone can offer will be greatly appreciated!


Last changed: November 20, 2007