Quality Acceptance Methods

Acceptance Sampling Method

A statistical sampling approach is widely used to decide whether or not to accept or reject a production lot without checking every single item of the lot. Randomly inspecting finished products once the products have been completed and packed is used by JitVerify just like most other inspection companies.

Focus on Acceptable Quality Levels

As a default, JitVerify inspectors use the MIL STD 105D tables (also known as AQL tables) to establish acceptable levels of quality of the products they inspect. These tables are a US standard with equivalents in all national and international standardization organizations.

How Do I Determine the Right Sample Size and Acceptance Number?

For a hypothetical inspection of a 1,000-unit lot, with an Acceptable Quality Level of II, Table II-A indicates that the sampling size should be 80 units. For an AQL of 2.5, the corresponding acceptance number is 3. In this case, the lot is rejected if 4 samples are found to be unacceptable.

Social Accountability Standards

Much like ISO 9000 for quality management and IS0 14000 for environmental management, the SA 8000 provides a set of standards for evaluating social accountability in the following areas:

  • Child labor: Companies must not use child labor. The Social Accountability International (SAI) standard defines child labor as the work of "any person under 15 years of age, unless local minimum age law stipulates a higher age for work."
  • Forced labor: Companies must not use "forced labor."
  • Health and safety: Companies must provide a safe and healthy working environment for their employees.
  • Freedom of association and right to collective bargaining: Companies must respect the right of all employees to form and join trade unions of their choice and to bargain collectively.
  • Discrimination: Companies shall not engage in or support discrimination in hiring, compensation, access to training, promotion, termination or retirement based on race, caste, national origin, religion, disability, gender, sexual orientation, union membership, or political affiliation.
  • Disciplinary practices: Companies must not engage in or support the use of corporal punishment, mental or physical coercion or verbal abuse.
  • Working hours: Companies must comply with applicable laws and industry standards on working hours.
  • Compensation: Companies must ensure that wages paid for a standard working week meet at least legal or industry minimum standards.
  • Management systems: Top management must define the company's policy for social accountability and labor conditions to ensure that it includes a commitment to conform to all requirements of this standard and national and other applicable laws.

Glossary

Acceptance Sampling
Acceptance Sampling is used to decide whether to accept or reject a production lot. It is performed once the production lot has been completed and packed. Basic procedures for Acceptance Sampling:

  • select a sample from a production lot,
  • inspect the units in the sample, and
  • use the result to decide whether or not to accept or reject the lot.

AQL (Acceptable Quality Levels)
JitVerify uses the Acceptable Quality Level (AQL) to establish a maximum allowable error rate or variation from the standard. Acceptance testing will stop if the failure rate of the product being tested exceeds the minimum Acceptable Quality Level.

Batch/Lot
A batch or lot is a collection of products – all identical in size, type, conditions and time of production – from which a sample will be taken to decide whether or not it conforms to the acceptance inspection.

Critical Defect
The Critical Defect corresponds to a defect likely to result in unsafe conditions for end-users. JitVerify’s default Critical Defect AQL is 0.

Defect classification
Defects detected during inspections are generally classified in 3 categories:

  • Critical defect
  • Major defect
  • Minor defect

Pre Shipment Inspection (PSI)
This is carried out when at least 80% of the goods ordered are export packed. Samples are selected at random, according to sampling standards and procedures. The inspection ensures that the production is in accordance with the specifications, purchase orders or letters of credit.

Inspection Level
This refers to the relation between the size of the lot and the size of the sample inspected. The Quality Level may be chosen between I, II, or III; JitVerify uses Level II by default.

Lot size
The lot size is the total number of units available for random sampling. The lot size only includes packed products.

Major defect
A Major defect corresponds to any defect, excluding Critical Defects that is likely to result in failure, or reduced usability of the product unit. A product is said to have a Major Defect when it is not dangerous but cannot be sold because of the defect. JitVerify’s default Major Defect AQL is 2.5.

MIL-STD 105D and 105E
JitVerify inspectors use the MIL-STD-105D (superseded by ISO 2859) tables for sampling. The tables are recognized by every industrial company. These American standards have equivalents in all national and international standardization organizations. These standards are proven methods to accept or reject a lot by inspecting a randomly selected number of products.

Minor Defect
A Minor defect corresponds to a defect that is not likely to reduce the usability of the product unit for its intended purpose, or is a departure from established standards having little bearing on the effective use or operation of the unit. A Minor Defect is nevertheless a workmanship defect beyond the defined quality standard. JitVerify’s default Minor Defect AQL is 4.0.

Rejection Number
The Rejection Number is equal to the acceptance number + 1 and represents the number of defective units from which the lot is discarded. If the total number of sampled products presenting this type of defect is equal or larger than the rejection number, the production has failed.

SA 8000
Consumers, customers and other interested parties have become increasingly concerned about whether products have been manufactured in accordance with human rights, child labor laws and non-discriminatory business practices. Released in October 1997, the Social Accountability 8000 (or SA 8000) Standard is the first global ethical standard. Its objective is to ensure fair sourcing and production of goods and services.

Sampling Level
The Sampling Level represents the global accuracy level of the Sampling Method. For a given lot size, increasing the Sampling Level means increasing the Sample Size. This improves accuracy but also increases the time needed to complete the inspection. The Quality Level may be chosen between I, II, or III. JitVerify’s default Quality Level is II which is the most common level used in the industry.

Sample Size
The sample size is the total number of units to be inspected.