Quality : Various  definitions

Business has tried to define quality in a producer-consumer context, with the following variations:

1. ISO 9000: "Degree to which a set of inherent characteristic fulfills requirements."^[2] The standard defines requirement as need or expectation.
2. Six Sigma: "Number of defects per million opportunities."^[3] The metric is tied in with a methodology and a management system.
3. Philip B. Crosby: "Conformance to requirements."^[4][5]customer expectations; Crosby treats this as a separate problem. The difficulty with this is that the requirements may not fully represent
4. Joseph M. Juran: "Fitness for use."^[5] Fitness is defined by the customer.
5. Noriaki Kano and others, presenting a two-dimensional model of quality: "must-be quality" and "attractive quality."^[6] The former is near to the "fitness for use" and the latter is what the customer would love, but has not yet thought about. Supporters characterize this model more succinctly as: "Products and services that meet or exceed customers' expectations."
6. Robert Pirsig: "The result of care."^[7]
7. Genichi Taguchi, with two definitions:

   a. "Uniformity around a target value."^[8] The idea is to lower the standard deviation in outcomes, and to keep the range of outcomes to a certain number of standard deviations, with rare exceptions.

   b. "The loss a product imposes on society after it is shipped."^[9] This definition of quality is based on a more comprehensive view of the production system.

8. American Society for Quality: "a subjective term for which each person has his or her own definition. In technical usage, quality can have two meanings:

   a. the characteristics of a product or service that bear on its ability to satisfy stated or implied needs;

   b. a product or service free of deficiencies."^[5]

9. Peter Drucker: "Quality in a product or service is not what the supplier puts in. It is what the customer gets out and is willing to pay for."^[10]

The common element of the business definitions is that the quality of a product or service refers to the perception of the degree to which the product or service meets the customer's expectations. Quality has no specific meaning unless related to a specific function and/or object. Quality is a perceptual, conditional and somewhat subjective attribute.

[edit] Improvement of quality

Many techniques and concepts, often overlapping, have evolved to improve product or service quality, including:

W. Edwards Deming, concentrating on "the efficient production of the quality that the market expects,"^[11] linked quality and management: "Costs go down and productivity goes up as improvement of quality is accomplished by better management of design, engineering, testing and by improvement of processes."^[12]