Quality Level - AQL
Quality Level. AQL . Also known as Assured Quality Level.
This publication establishes lot or batch sampling plans and procedures
for quality inspection by attributes. The sampling plans described
in this standard are applicable to AQL of 0.01 % or higher and are
therefore not suitable for applications where quality level in the
defective parts per million range cab be realized.
These plans are intended primarily to be used for a continuing series
of lot or batch. The plan may also be used for the the inspection
of isolated lot or batch.
- AQL Keyword listing
Quality Level - AQL - What is AQL?
When a continuous series of lots is considered, the AQL is the quality
level which, for the purposes of sampling inspection, is the limit
of a satisfactory process average.
A sampling plan and an AQL are chosen in accordance with the risk
assumed. Use of the value of AQL for certain defect or group of
defects indicates that the sampling plan will accept the great majority
of the lot or batch provided the process average level of percentage
defective in these lot or batch be no greater than the designated
value of AQL sampling plan.
outgoing quality - AOQ
For a particular process average, the AOQ is the average quality
of outgoing product including all accepted lot or batch, plus all
rejected lot or batch after the rejected lot or batch have been
effectively 100 % inspected and all defectives replaced by non-defectives.
Classification of Defects
A classification of defects is the enumeration of possible defects
of the unit of product classified according to their seriousness.
Lot or batch
The term lot or batch shall mean " inspection lot " or
" Inspection batch " . The lot or batch size is the number
of units of product in a lot or batch.
The process average is the average percent defective or average
number of defects per hundred units of product committed by the
supplier for original inspecting. Original inspection is the first
inspection of a particular quantity of product as distinguished
from the inspection of product which has been resubmitted after
A sample consists of one or more units of product drawn from a lot
or batch, the unit of the sample being selected at random without
regard to their quality. The number of units of product in the sample
is the AQL sample size.
A sampling plan indicates the number
of unit of product from each lot or batch which are to be insppected
and the criteria for determining the acceptability of the lot or
The unit of product is the thing inspected in order to determine
its classication as defective or non-defective or to count the number
of defects. It may be a single article, a pair, a set, a length
or the end product itself. The unit of product may or may not be
the same as the unit of purchase, supply or shipment.
Sampling plans | Master table
quality sampling plan