Acceptable quality level (AQL)

The poorest level of quality from a supplier's process that would be considered acceptable as a process average. You want to design a sampling plan that accepts a particular lot of product at the AQL most of the time.

For example, you receive a shipment of microchips and your acceptable quality level (AQL) is 1.5%. Realizing that you won't always make the correct decision (sampling risk) you set the producer's risk (alpha) at 0.05. This means that approximately 95% of the time you will correctly accept a lot with a quality level of 1.5% or better and 5% of the time you will incorrectly reject the lot with a quality level of 1.5% or better.

While the AQL describes what the sampling plan will accept, the rejectable quality level (RQL) describes what the sampling plan will reject.