Acceptable quality level, the percent defective at which a sampling plan is designed to accept lots with high probability, typically about 95 percent; the rejection chance at that level is the producer's risk. An AQL of 1.0 does not mean 1 percent defective is acceptable in the contract sense; it sets where the plan's operating characteristic curve sits. Lots far worse than the AQL can still pass when the sample is small.
Supplier keeps quoting AQL 0.65 like it's a guarantee. It's a sampling setting, not a ppm promise.
Also heard as
- acceptable quality level
- acceptance quality limit
Do not mix it up with
- LTPD: AQL marks the good-quality end that a plan should accept; LTPD marks the poor-quality end that it should reject.
Related terms
LTPD
Lot tolerance percent defective: the poor quality level that a sampling plan should reject with high probability.
Operating characteristic curve
Graph of a sampling plan's probability of accepting a lot against the lot's true defect rate.
Acceptance sampling
Accepting or rejecting a whole lot based on inspecting a random sample from it against a predefined plan.