By John N. Zorich
The pros and cons of the 2 most widely used sampling plans (ANSI Z1.4, and Squeglia’s C=0) are examined in detail, focusing especially on the weaknesses of such plans in regards to meeting regulatory requirements. Real-world examples are provided for how using such sampling plans leads to production of non-conforming product.
The advantages of “confidence/reliability” calculations are explained. Such calculations are demonstrated for Attribute data (pass/fail, yes/no data) as well as for variables data (i.e., measurements). If variables data is “Normally distributed” the calculations are extremely simple. The webinar explains how to handle “non-Normal” data, and provides the methods, formulas, and tools to handle non-normality.
The webinar includes a discussion of how one OEM manufacturer has implemented “confidence/reliability” calculations instead of AQL sampling plans for all of its clients. And suggestions are given for how to use “confidence/reliability” QC specifications instead of “AQL” QC specifications. The use of “reliability plotting” for assessing product reliability during R&D is also discussed. The webinar also includes an examination of ISO and FDA regulations and guidelines regarding the use of statistics, especially in regards to Sampling Plans.