acceptable quality level , AQL (abbreviation)

Two quality levels are decided, the acceptable quality level (AQL) and the lot tolerance percentage defective (LTPD).

An acceptable quality level is a test and/or inspection standard that prescribes the range of the number of defective components that is considered acceptable when random sampling those components during an inspection.

Acceptance sampling is usually carried out at the customer's premises and consists of examining samples of goods delivered, noting the number of reject, or unsatisfactory, items, comparing this number with an agreed acceptable quality level.

The acceptable quality limit (AQL) is the worst tolerable process average (mean) in percentage or ratio that is still considered acceptable; that is, it is at an acceptable quality level.

In a quality control procedure, a process is said to be at an acceptable quality level if the appropriate statistic used to construct a control chart does not fall outside the bounds of the acceptable quality limits.

This is where the customer samples a batch of newly delivered goods, and either rejects or accepts the batch on the basis of an acceptable quality level, usually a small percentage of rejects per batch.