C=0 Sampling for Variable Characteristics

Mike S.

An Early 'Cover'
#11
C=0 attribute sampling is often required by certain customers/industries.

Converting variable data to pass/fail for use in a sampling plan is easy for operators to use.

If you can easily record your variable data in a time-oriented fashion as the parts are produced, you can easily use that data in a control chart and, if allowed, monitor your process for statistical control and conformance to specification at the same time.

Hope that answers your question. Maybe I did not understand it correctly.
 

Bev D

Heretical Statistician
Staff member
Super Moderator
#12
Bump

We have been using the C=0 Sampling plan for all Lot By Lot incoming inspections, where variable dimensional data is recorded. Where a dimension is found to be out of specification on one sample, the batch is either rejected or 100% inspected.

Can anyone provide an acceptable rationale for using C=0 for variable date instead of a sampling plan such as ANSI Z1.9?

Thanks
I don't think I can come up with a rational to NOT use an attribute sampling plan other than for some very unique situations.

I can come up with reasons to not use the c=0 concept, but that is so deeply embedded in our folklore that has achieved 'zombie theory' status...
 
#13
BSI just did an (medical device mfg) audit. This auditor is saying any characteristics that are considered variable and part of the inspection plan, the actual data points vs acc/rej, will have to be documented on the inspection plan. Our sampling is based upon, ANSI/ASQ Z 1.4. To minimize questions ... does the FDA require "actuals" to be documented encompassing receiving inspection. Clarification of 21CFR820, Sec 820.80. Another words, This holds true, "I could be on one lot for days"
 

Al Rosen

Staff member
Super Moderator
#14
BSI just did an (medical device mfg) audit. This auditor is saying any characteristics that are considered variable and part of the inspection plan, the actual data points vs acc/rej, will have to be documented on the inspection plan. Our sampling is based upon, ANSI/ASQ Z 1.4. To minimize questions ... does the FDA require "actuals" to be documented encompassing receiving inspection. Clarification of 21CFR820, Sec 820.80. Another words, This holds true, "I could be on one lot for days"
Did he write a finding or is this opinion? Opinions mean nothing. If he wrote a finding, what requirement did he write it against?
 
#15
Did he write a finding or is this opinion? Opinions mean nothing. If he wrote a finding, what requirement did he write it against?
Good question, will find out. Then again, our QA staffers would probably jump off a bridge if asked to do so. I appreciate the prompt response, will post the answer. Drew
 

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