Nonconformity (quality)

In quality management, a nonconformity (also known as a defect) is a deviation from a specification, a standard, or an expectation. Nonconformities are classified as either critical, major, or minor.^[1]

In software engineering, ISO/IEC 9126 distinguishes between a defect and a nonconformity; a defect is the nonfulfilment of intended usage requirements, whereas a nonconformity is the nonfulfilment of a requirement. A similar distinction is made between validation and verification.

Types

• Minor nonconformity – Any nonconformity which does not adversely affect the performance, durability, interchangeability, reliability, maintainability, effective use or operation, weight or appearance (where a factor), health or safety of a product. Multiple minor nonconformities when considered collectively may raise the category to a major or critical nonconformity.^[2]
• Major nonconformity – Any nonconformity other than critical, which may result in failure or materially reduce the usability of the product for the intended purpose (i.e. effective use or operation, weight or appearance (where a factor), health or safety) and which can not be completely eliminated by rework or reduced to a minor nonconformity by an approved repair.^[2]
• Critical nonconformity – Any nonconformity which may result in hazardous or unsafe conditions for individuals using, maintaining or depending upon the product or prevent performance of a vital agency mission.^[2]

References

1. Richard C. Dorf (1999). The Technology Management Handbook. CRC Press. pp. 13—34. ISBN 9780849385773.
2. General Services Administration, Department of Defense, National Aeronautics and Space Administration: Federal Acquisition Regulation, March 2005.