Software Design for Six Sigma: A Roadmap for Excellence

Chapter 1. SOFTWARE QUALITY CONCEPTS

WHAT IS QUALITY

The American Heritage Dictionary defines quality as "a characteristic or attribute of something." Quality is defined in the International Organization for Standardization (ISO) publications as the totality of characteristics of an entity that bear on its ability to satisfy stated and implied needs.

Quality is a more intriguing concept than it seems to be. The meaning of the term "Quality" has evolved over time as many concepts were developed to improve product or service quality, including total quality management (TQM), Malcolm Baldrige National Quality Award, Six Sigma, quality circles, theory of constraints (TOC), Quality Management Systems (ISO 9000 and ISO 13485), axiomatic quality (El-Haik, 2005), and continuous improvement. The following list represents the various interpretations of the meaning of quality:

• "Quality: an inherent or distinguishing characteristic, a degree or grade of excellence" (American Heritage Dictionary, 1996).

• "Conformance to requirements" (Crosby, 1979).

• "Fitness for use" (Juran & Gryna, 1988).

• "Degree to which a set of inherent characteristic fulfills requirements" ISO 9000.

• "Value to some person" (Weinberg).

• "The loss a product imposes on society after it is shipped" (Taguchi).

• "The degree to which the design vulnerabilities do not adversely affect product performance" (El-Haik, 2005).

Quality is a characteristic that a product or service must have. It refers to the perception of the degree to which the product ...