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What Are Quality Assurance and Quality Control?


By the ASQ Audit Division and J. P. Russell, editor

Quality Glossary Definition: Quality assurance/quality control (QA/QC)

Two terms that have many interpretations because of the multiple definitions for the words assurance and control…. One definition of quality assurance is: all the planned and systematic activities implemented within the quality system that can be demonstrated to provide confidence that a product or service will fulfill requirements for quality. One definition for quality control is: the operational techniques and activities used to fulfill requirements for quality. Often, however, “quality assurance” and “quality control” are used interchangeably, referring to the actions performed to ensure the quality of a product, service or process.

What is quality management?

Quality has been defined as fitness for use, conformance to requirements, and the pursuit of excellence. Even though the concept of quality has existed from early times, the study and definition of quality have been given prominence only in the last century.

1920s: quality control. Following the Industrial Revolution and the rise of mass production, it became important to better define and control the quality of products. Originally, the goal of quality was to ensure that engineering requirements were met in final products. Later, as manufacturing processes became more complex, quality developed into a discipline for controlling process variation as a means of producing quality products.

1950s: quality assurance and auditing. The quality profession expanded to include the quality assurance and quality audit functions. The drivers of independent verification of quality were primarily industries in which public health and safety were paramount.

1980s: total quality management (TQM). Businesses realized that quality wasn’t just the domain of products and manufacturing processes, and total quality management (TQM) principles were developed to include all processes in a company, including management functions and service sectors.

Quality management today. There have been many interpretations of what quality is, beyond the dictionary definition of “general goodness.” Other terms describing quality include reduction of variation, value-added, and conformance to specifications.

ISO 9000:2015: Quality management systems—Fundamentals and vocabulary defines quality as the  “degree to which a set of inherent characteristics of an object  fulfils requirements.” Simply stated, quality is meeting customer requirements.

A system of quality management includes all activities of the overall management function that determine the quality policy, objectives, and responsibilities and their implementation. As ISO 9000 explains, a management system provides the means of establishing a policy and objectives and the means to achieve those objectives.

Difference between quality assurance and quality control

Quality assurance and quality control are two aspects of quality management. While some quality assurance and quality control activities are interrelated, the two are defined differently. 

According to ISO 9000:2015: Quality management systems—Fundamentals and vocabulary:

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Quality assurance consists of that “part of quality management focused on providing confidence that quality requirements will be fulfilled.” The confidence provided by quality assurance is twofold—internally to management and externally to customers, government agencies, regulators, certifiers, and third parties.

Quality control is that “part of quality management focused on fulfilling quality requirements.”

While quality assurance relates to how a process is performed or how a product is made, quality control is more the inspection aspect of quality management.

Inspection is the process of measuring, examining, and testing to gauge one or more characteristics of a product or service and the comparison of these with specified requirements to determine conformity. Products, processes, and various other results can be inspected to make sure that the object coming off a production line, or the service being provided, is correct and meets specifications.

Industry perspectives on assurance and control

For some service organizations, the concept of quality control may be foreign because there is no tangible product to inspect and control. The quality assurance function in a service organization may not include quality control of the service but may include quality control of any products involved in providing the service.

A service may include products that are documents (such as a report, contract, or design) or tangible products such as a rental car or units of blood. It may be necessary to control product quality in a service organization to ensure that the service meets customer requirements.

Quality assurance and audit functions

Auditing is part of the quality assurance function. It is important to ensure quality because it is used to compare actual conditions with requirements and to report those results to management.

In The Quality Audit: A Management Evaluation Tool (McGraw-Hill, 1988), Charles Mill wrote that auditing and inspection are not interchangeable: “The auditor may use inspection techniques as an evaluation tool, but the audit should not be involved in carrying out any verification activities leading to the actual acceptance or rejection of a product or service. An audit should be involved with the evaluation of the process and controls covering the production and verification activities.”  

Formal management systems have evolved to direct and control organizations. There are quality management systems (QMSs) as well as environmental or other management systems, and each of these systems may be audited.  

Excerpted from “Appendix E: History of Quality Assurance and Auditing,” from The ASQ Auditing Handbook, by the ASQ Audit Division and J.P. Russell, editor, ASQ Quality Press, 2012, pages 299-301.

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