AS9138 Sample Size Determination


Starting to get Involved
Here's my situation. Customer requirements call for sampling under AS9138 Table A1, which I understand to describe 1 minus the IRR, per my reading of § 4.4.2(e).

No AQL is mentioned in the customer requirements.

AS9138 refers me to the tables in SCMH § 3.7.4 for sample sizes. Those tables are based on AQL, rather than IRR. So I'm off to look for a conversion table.

I find the IAQG's AS9138 FAQ. FAQ #20 provides an AQL to IRR conversion table, but warns "This conversion process does not work backwards. If a specification has given an IRR, it is important not to use an AQL method to replace it."

I am thus at a loss to get from AS9138 Table A1 to the appropriate sample size table in in SCMH § 3.7.4.

Any assistance would be appreciated.


You should point that descreptancy out to your customer and ask for guidance. They should fix it, but often things like this are ignored. Put it on their shoulders and keep a record of it including any additional communication about it.

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