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Quality Glossary - N


n: The number of units in a sample.

N: The number of units in a population.

Nagara system: Smooth production flow, ideally one piece at a time, characterized by synchronization (balancing) of production processes and maximum use of available time; includes overlapping of operations where practical. A nagara production system is one in which seemingly unrelated tasks can be produced simultaneously by the same operator.

National Institute of Standards and Technology (NIST): An agency of the U.S. Department of Commerce that develops and promotes measurements, standards and technology, and manages the Malcolm Baldrige National Quality Award.

Natural team: A team of individuals drawn from a single work group; similar to a process improvement team except that it is not cross functional in composition and it is usually permanent.

Next operation as customer: The concept of internal customers in which every operation is both a receiver and a provider.

Nominal group technique: A technique, similar to brainstorming, to generate ideas on a particular subject. Team members are asked to silently write down as many ideas as possible. Each member is then asked to share one idea, which is recorded. After all the ideas are recorded, they are discussed and prioritized by the group.

Nonconforming record (NCR): A permanent record—made in writing—for accounting and preserving the knowledge of a nonconforming condition for the purposes of documenting facts or events.

Nonconformity: The nonfulfillment of a specified requirement. Also see “blemish,” “defect” and “imperfection.”

Nondestructive testing and evaluation (NDT, NDE): Testing and evaluation methods that do not damage or destroy the product being tested.

Nonlinear parameter estimation: A method whereby the arduous and labor intensive task of multiparameter model calibration can be carried out automatically under the control of a computer.

Nonparametric tests: All tests involving ranked data (data that can be put in order). Nonparametric tests are often used in place of their parametric counterparts when certain assumptions about the underlying population are questionable. For example, when comparing two independent samples, the Wilcoxon Mann-Whitney test (see listing) does not assume that the difference between the samples is normally distributed, whereas its parametric counterpart, the two-sample t-test, does. Nonparametric tests can be, and often are, more powerful in detecting population differences when certain assumptions are not satisfied.

Nonvalue added: A term that describes a process step or function that is not required for the direct achievement of process output. This step or function is identified and examined for potential elimination. Also see “value added.”

Norm (behavioral): Expectations of how a person or persons will behave in a given situation based on established protocols, rules of conduct or accepted social practices.

Normal distribution (statistical): The charting of a data set in which most of the data points are concentrated around the average (mean), thus forming a bell shaped curve.

Number of affected units chart: A control chart for evaluating the stability of a process in terms of the total number of units in a sample in which an event of a given classification occurs.