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.Dodge, Y. (2003) ''The Oxford Dictionary of Statistical Terms''. OUP. Closely related terms are the rejectable quality limit and rejectable quality level (RQL). In a

quality control Quality control (QC) is a process by which entities review the quality of all factors involved in production. ISO 9000 defines quality control as "a part of quality management focused on fulfilling quality requirements". This approach places ...

procedure, a process is said to be at an acceptable quality level if the appropriate statistic used to construct a

control chart Control charts is a graph used in production control to determine whether quality and manufacturing processes are being controlled under stable conditions. (ISO 7870-1) The hourly status is arranged on the graph, and the occurrence of abnormalit ...

does not fall outside the bounds of the acceptable quality limits. Otherwise, the process is said to be at a rejectable control level. In 2008 the usage of the abbreviation AQL for the term "acceptable quality limit" was changed in the standards issued by at least one national

standards organization A standards organization, standards body, standards developing organization (SDO), or standards setting organization (SSO) is an organization whose primary function is developing, coordinating, promulgating, revising, amending, reissuing, interpr ...

(

ANSI The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...

/ ASQ) to relate to the term "acceptance quality level".http://www.aqlinspectorsrule.com/Z1-4-2008.html ''AQL Inspectors Rule'' It is unclear whether this interpretation will be brought into general usage, but the underlying meaning remains the same. 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 In statistics, quality assurance, and survey methodology, sampling is the selection of a subset (a statistical sample) of individuals from within a statistical population to estimate characteristics of the whole population. Statisticians attemp ...

those components during an inspection. The defects found during an electronic or electrical test, or during a physical (mechanical) inspection, are sometimes classified into three levels: critical, major and minor. Critical defects are those that render the product unsafe or hazardous for the end user or that contravene mandatory regulations. Major defects can result in the product's failure, reducing its marketability, usability or saleability. Lastly, minor defects do not affect the product's marketability or usability, but represent

workmanship Workmanship is a human attribute relating to knowledge and skill at performing a task. Workmanship is also a quality imparted to a product. The type of work may include the creation of handcrafts, art, writing, machinery and other products. Workma ...

defects that make the product fall short of defined quality standards. Different companies maintain different interpretations of each defect type. In order to avoid argument, buyers and sellers agree on an AQL standard, chosen according to the level of

risk In simple terms, risk is the possibility of something bad happening. Risk involves uncertainty about the effects/implications of an activity with respect to something that humans value (such as health, well-being, wealth, property or the environme ...

each party assumes, which they use as a reference during pre-shipment inspection.

See also

References

Further reading