We use the well-proven and widely adopted international standard ANSI/ASQC Z1.4-2003 (equivalent to MIL-STD-105e, ISO2859, NF06-022, BS6001, DIN40080, and GB2828) to measure the acceptable quality level of the products we inspect.
How do I determine the right sample size and acceptance number?
For example, the order quantity is 12,000 and we select general inspection levels-II (see Table A) to be as the sampling method, then we can get sample size code letter L (see Table A). With this code letter, and if we take the single sampling plan for normal inspection, we can get the sample size: 200 from table B. It means that 200 samples can well represent this order. For an AQL of 0.15, the corresponding acceptance number is 1 and the rejection is 2.
As default, we use general inspection level II, Single sampling plan, and the AQL of:
- Critical Defects: 0
- Major Defect: AQL 2.5
- Minor Defect: AQL 4.0
For example, if there's an order with 6,000 products, then according to CIS's default sampling technique, the sample size will be: 200 products. The maximum acceptable defect number will be:
- Critical Defects: 0 Defective Products
- Major Defect: 10 Defective Products
- Minor Defect: 14 Defective Products