Technical terms of quality management: N



National Accreditation Council for Certification Bodies. Former national British accreditation body. See UKAS.



Normenausschuss Grundlagen des Umweltschutzes im DIN [DIN Standards Committee Principles of Environmental Protection].


National measurement standard

Recognized measurement standard for a specific physical quantity. It forms the basis for the determination of the characteristic value of all other measurement standards of the quantity in question. An official national ruling is the basis for the recognition in a country. (On the basis of DIN 1319-1)



Non-destructive testing.


New Seven

Also: New Seven Tools for Quality Control. See Management tools.



National Institute of Standards and Technology, Gaithersburg (USA). www.nist.gov


Nominal value

Characteristic value of a quantitative characteristic in order to divide up the scope. (On the basis of DIN 55350-12)



  1. Also called a failure, fault, or error. Failure to fulfill a requirement. (On the basis of ISO 9000:2015)
  2. Non-fulfillment of a requirement.

Nonconformity classification, classification of nonconformities

Classification of a unit‘s potential nonconformities into nonconformity classes. The evaluation depends on the effects of the nonconformity. Internationally, nonconformities are divided into three nonconformity classes: Critical nonconformities: – Major nonconformities – Minor nonconformities. (On the basis of DGQ Volume 11-04:2012)


Nonconformity costs, costs of nonconformity

Also called cost of failure. Costs resulting from a nonconformity. Nonconformities result in costs. Nonconformity costs can be divided into two groups, depending on where they were found: internal nonconformity costs and external nonconformity costs. An organization should define what it sees as internal and external failure costs. DIN 55350-11 gives these examples of nonconformity costs: Costs for remedying or mitigating a nonconformity, for rework, repair, scrapping, disposal, handling of rejects, unplanned sorting test, repeated inspection, downtime, guarantee and product liability. (On the basis of DIN 55350-11)


Nonconformity criterion

Characteristic that can be used to determine if there is a nonconformity.
(DGQ Volume 11-04:2009)


Nonconformity prevention

Development of products and production processes in order to manufacture conforming products. (On the basis of ISO 16949-2009)


Nonconformity weighting, weighting of nonconformities

Classification of a unit‘s possible nonconformities into nonconformity weight classes. This classification takes place after the nonconformities have been rated according to their weight (nonconformity‘ s significance for the organization).


Normal distribution

The distribution behavior of a process in control usually follows a typical pattern. The most commonly occurring dispersion pattern is the (Gaussian) normal distribution. It occurs when bilateral variability around a target value is exclusively due to random causes.



Designation of an accreditation body for the performance of conformity assessment procedures on the basis of an EU directive.



Normenausschuss Grundlagen des Umweltschutzes im DIN [DIN Standards Committee Principles of Environmental Protection


Null hypothesis

Statement that is used to select a subset. This subset is determined from the probability distribution allowed for the statistical test as a whole. (On the basis of DGQ Volume 11-04:2012)

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