Focus on Acceptable Quality Levels
VietEyes Inspection quality inspectors use the ISO 2859 tables (also known as AQL tables) to measure acceptable levels of quality. These tables are a US standard with equivalents in all national and international standardization organizations (ANSI/ASQC Z1.4, ISO 2859, NF06-022, BS 6001, DIN 40080). Here are some questions and answers:

(q) How do I determine the right sample size and acceptance number?
(a) For a hypothetical inspection of a 4,000-unit lot, with an Acceptable Quality Level of II (MIL-STD-105E), Sample size table indicates that the sampling size should be 200 units. For an AQL of 2.5, the corresponding acceptance number is 10.

(q) What does this mean in concrete terms?
(a) If the number of defective units is higher than 10, the lot has to be rejected. If the lot is accepted, it is understood to contain a maximum of 2.5% defective units (with a failure risk of less than 5%).

(q) What should I do with defective or discarded lots?
(a) Defective items found as part of 100% inspection can be discarded, repaired or replaced. You may also opt to sell the discarded lot at a discount.

Sample size code letter table

Single sampling plans for normal inspection