Q: I have ANSI/ASQ Z1.4-2008 Sampling Procedures and Tables for Inspection by Attributes. I looked through it rapidly, and I still can’t find the C=0 plan directly, so I am a little confused. I thought C=0 is included in Z1.4. Is the C=0 plan spirit/concept contained in Z1.4 or does C=0 need to be calculated from the several tables in Z1.4? (if yes, which tables?).
A: Z1.4:2008 is a general sampling plan for attributes. It is tabled by AQL with varying accept reject numbers. The standard gives a framework for attribute inspection plans. Though Z1.4 does have some plans where C=0, they are NOT optimal to minimize the Type II error. For C=0 plans specifically, I would recommend purchasing Zero Acceptance Number Sampling Plans, Fifth Edition. The value of the Z1.4 standard is the switching rules used for incoming inspection.
Secretary, U.S. TAG to ISO/TC 69
Statistician, GE Healthcare
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