AQL Sampling Tables Question

B

baioce

#1
Hi,

I have been reading extensively about how acceptance sampling and do understand perfectly the AQL concept. What I dont understand and I cannot find an explanation for is the following.

Lets suppose that I have a lot of 100,000 and I want a maximum of 1% defects. Based on the table below I would be sampling 500 products and accepting <=10. My question is: How do they come up with 10? If this is based of a 1-sided binomial distribution, if I plug in those numbers at a 95% confidence I get that the maximum that I can accept is 1 defective product in the sample. So, how come they are saying 10? How do they come up with that number? What am I missing?

Thanks so much for the help
 

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Bev D

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#4
Well, the formula you used is not the formula the AQL tables are based on.
The AQL tables were based on grouping of lot sizes and a lot size adjustment that isn't necessary and was the result of negotiations.

Remember that the AQL is the defect rate that will be accepted 95% of the time. (if your confidence level is 95%)

The manner in which you used the Binomial had your 1% defect rate as the RQL or Rejectable quality level (aka LTPD); the defect rate that you would detect and therefore reject 95% of the time. These are very different plans. This plan would give you an AQL of .07%

You may want to check out this AQL RQL Spreadsheet developed by some of us at the cove rather than the AQL tables. The formulas are listed in the spreadsheet so you can understand how calculations are being done.
 
Last edited:
B

baioce

#5
Hi,

Thanks so much. I will take a look and will let you know if there is anything I cannot figure out.

Thanks again for your help!
 
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