Quality Glossary

Acceptance number:

The maximum number of defects or defectives allowable in a sampling lot for the lot to be acceptable.


Certification by a recognized body of the facilities, capability, objectivity, competence and integrity of an agency, service or operational group or individual to provide the specific service or operation needed. The term has multiple meanings depending on the sector. Laboratory accreditation assesses the capability of a laboratory to conduct testing, generally using standard test methods. Accreditation for healthcare organizations involves an authoritative body surveying and verifying compliance with recognized criteria, similar to certification in other sectors.

Accreditation body:

An organization with authority to accredit other organizations to perform services such as quality system certification.

American Society for Quality (ASQ):

A professional, not-for-profit association that develops, promotes and applies quality-related information and technology for the private sector, government and academia. ASQ serves individual and organizational members in more than 140 countries.

ASQ certification:

ASQ certification exams take place multiple times a year and each have their own application deadline. A strategy for preparing for your ASQ certification exam is by taking our ASQ exam prep courses.


The on-site verification activity, such as inspection or examination, of a process or quality system, to ensure compliance to requirements. An audit can apply to an entire organization or might be specific to a function, process or production step.


A technique in which a company measures its performance against that of best-in-class companies determines how those companies achieved their performance levels and uses the information to improve its own performance. Subjects that can be benchmarked include strategies, operations and processes.

Best practice:

A superior method or innovative practice that contributes to the improved performance of an organization, usually recognized as best by other peer organizations.

Big Q, little q:

A term used to contrast the difference between managing for quality in all business processes and products (big Q) and managing for quality in a limited capacity—traditionally only in factory products and processes (little q).

Body of knowledge (BOK):

The prescribed aggregation of knowledge in a particular area an individual is expected to have mastered to be considered or certified as a practitioner.

Capability maturity model (CMM)

A framework that describes the key elements of an effective software process. It’s an evolutionary improvement path from an immature process to a mature, disciplined process. The CMM covers practices for planning, engineering and managing software development and maintenance to improve the ability of organizations to meet goals for cost, schedule, functionality and product quality.

Case studies:

A case study is about a particular product or service purchased by a customer then discussed with its specifications and end applications to illustrate its usage and results. Read the IQPS case studies to see how our services and Quality courses have helped others.

Cause analysis:

Another term for root cause analysis.

Cause and effect diagram:

A tool for analyzing process dispersion. It is also referred to as the “Ishikawa diagram,” because Kaoru Ishikawa developed it, and the “fishbone diagram,” because the complete diagram resembles a fish skeleton. The diagram illustrates the main causes and subcauses leading to an effect (symptom). The cause and effect diagram is one of the “seven tools of quality.”


The result of a person meeting the established criteria set by a certificate granting organization.

Certified Biomedical Auditor (CBA):

An ASQ certification.

Certified Calibration Technician (CCT):

An ASQ certification.

Certified HACCP Auditor (CHA):

An ASQ certification.

Certified Quality Auditor (CQA):

An ASQ certification that involves a CQA exam. The Certified Quality Auditor (CQA) professional understands the standards and principles of auditing. The auditing techniques of examining, questioning, evaluating and reporting to determine a quality system’s adequacy and deficiencies are germane to the Certified Quality Auditor’s job description. The Certified Quality Auditor (CQA) analyzes all elements of a quality system and judges its degree of adherence to the criteria of industrial management, quality evaluation and control systems. Innovative Quality Products and Systems offers a Certified Quality Auditor (CQA) course in preparation for certification. A quality auditor training course helps individuals to review the information that they will be tested on when taking the CQA exam.

Certified Quality Process Analyst (CQPA)

An ASQ certification.

Certified Quality Improvement Associate (CQIA):

An ASQ certification.

Certified Quality Technician (CQT):

An ASQ certification. A Certified Quality Technician inspects products to assure that they meet defined standards for durability, function, customer satisfaction or any other metric that the industry considers a measure of quality.

Certified Reliability Engineer (CRE):

An ASQ certification.

Certified Six Sigma Black Belt (CSSBB):

An ASQ certification.

Certified Six Sigma Green Belt (CSSGB):

An ASQ certification.

Certified Software Quality Engineer (CSQE):

An ASQ CSQE certification. IQPS offers a CSQE course that is based on the ASQ Body of Knowledge and provides a comprehensive presentation of all aspects of software quality engineering in preparation for the Certified Software Quality Engineer (CSQE) Examination.


A tool for ensuring all important steps or actions in an operation have been taken. Checklists contain items important or relevant to an issue or situation. Checklists are often confused with check sheets (see listing).

Check sheet:

A simple data recording device. The check sheet is custom designed by the user, which allows him or her to readily interpret the results. The check sheet is one of the “seven tools of quality” (see listing). Check sheets are often confused with checklists (see listing).

Code of conduct:

Expectations of behavior mutually agreed on by a team.

Common causes:

Causes of variation that are inherent in a process over time. They affect every outcome of the process and everyone working in the process. Also see “special causes.”

Company culture:

A system of values, beliefs and behaviors inherent in a company. To optimize business performance, top management must define and create the necessary culture.


The state of an organization that meets prescribed specifications, contract terms, regulations or standards.

Continuous quality improvement (CQI)

A philosophy and attitude for analyzing capabilities and processes and improving them repeatedly to achieve customer satisfaction.

Corrective action recommendation (CAR):

The full cycle corrective action tool that offers ease and simplicity for employee involvement in the corrective action/process improvement cycle in response to Root Cause Analysis.

Corrective action:

A solution meant to reduce or eliminate a problem identified by Root Cause Analysis.


A set of collected facts. There are two basic kinds of numerical data: measured or variable data, such as 16 ounces,4 miles” and 0.75″ and counted or attribute data, such as 162 defects.

Deming cycle:

Another term for the plan-do-study-act cycle. Walter Shewhart created it (calling it the plan-do-check-act cycle), but W. Edwards Deming popularized it, calling it plan-do-study-act.

Design of experiments (DoE)

A branch of applied statistics dealing with planning, conducting, analyzing and interpreting controlled tests to evaluate the factors that control the value of a parameter or group of parameters. Design for Six Sigma (DFSS).


The result of an action being taken; the expected or predicted impact when an action is to be taken or is proposed.


The state of having produced a decided on or desired effect.


The ratio of the output to the total input in a process.


A term describing a process that operates effectively while consuming minimal resources (such as labor and time).

Eighty-twenty (80-20):

A term referring to the Pareto principle, which was first defined by J. M. Juran in 1950. The principle suggests most effects come from relatively few causes; that is, 80% of the effects come from 20% of the possible causes. Also see “Pareto chart.”

Error detection:

A hybrid form of error proofing. It means a bad part can be made but will be caught immediately, and corrective action will be taken to prevent another bad part from being produced. A device is used to detect and stop the process when a bad part is made. This is used when error proofing is too expensive or not easily implemented.

Error proofing:

Use of process or design features to prevent the acceptance or further processing of nonconforming products. Also known as “mistake-proofing.”

Fishbone diagram:

See “cause and effect diagram.”

Five whys:

A technique for discovering the root causes of a problem and showing the relationship of causes by repeatedly asking the question, “Why?”

Gantt chart:

A type of bar chart used in process planning and control to display planned and finished work in relation to time.

Global quality:

The systematic design and implementation of quality processes across the world, based on information-sharing and best practices.


A graphic summary of variation in a set of data. The pictorial nature of a histogram lets people see patterns that are difficult to detect in a simple table of numbers. One of the “seven tools of quality.”

IATF 16949:

A harmonized set of supplier quality management system requirements for automotive suppliers released in October 2016 by the International Automotive Task Force (IATF). IATF 16949 replaced ISO/TS 16949.

IATF 16949 core tools course:

The IATF-16949 Core Tools Course provides a practical discussion and application of the required IATF-16949 Core Tools.

IATF 16949 executive overview:

Simplify your IATF-16949 implementation through proper understanding of key processes, definition of support processes, and identification of procedures. This executive overview is a course that IQPS offers that includes the identification of these processes and their strategic monitoring and measurement of goal deployment. Our IATF-16949 course satisfies the process ownership training requirement.


The products, services and material obtained from suppliers to produce the outputs delivered to customers.

Internal auditor:

An internal auditor prepares, performs, reports and closes an audit. IQPS (Innovative Quality Products and Systems) has Internal Auditor Training that is split into an internal audit training for manufacturers and one for software engineers. These onsite Internal Auditor Training courses are ideal for new auditors, those preparing to be on an audit team and people who will soon be audited and want to understand the auditing process.

Internal audit course:

An internal audit course is a course designed to supply individuals with the knowledge, skills, and training needed to perform successful internal audits. To learn more about the internal audit course IQPS offers, check out the course outline.

Internal audit training:

This internal audit course introduces the auditing function and registration process to both the novice and experienced internal auditor. Learn more about the Internal Auditor Training Course that IQPS offers.

International automotive task force (IATF):

A cooperative group of automotive manufacturers and others primarily responsible for the development and launch of International Organization for Standardization Technical Specification 16949.

Ishikawa diagram:

See “cause and effect diagram.”

ISO 14000:

An environmental management standard related to what organizations do that affects their physical surroundings.

ISO 9000 series standards:

A set of international standards on quality management and quality assurance developed to help companies effectively document the quality system elements to be implemented to maintain an efficient quality system. The standards, initially published in 1987, are not specific to any particular industry, product or service. The standards were developed by the International Organization for Standardization. The standards underwent major revision in 2000 and now include ISO 9000:2005 (definitions), ISO 9001:2008 (requirements) and ISO 9004:2009 (continuous improvement).

ISO 9001:

A voluntary quality management system standard developed by the International Organization for Standardization (ISO). First released in 1987 and one of several quality certifications in the ISO 9000 standards.

ISO 9001:2015:

This ISO standard applies to any organization, regardless of size or industry. More than one million organizations from more than 160 countries have applied the ISO 9001 standard requirements to their quality management systems.

ISO/TS 16949:

International Organization for Standardization international technical specification for quality management systems, with particular requirements for the application of ISO 9001:2008 for automotive production and relevant service part organization; generally replaced the U.S. QS-9000 standard. Now in its second edition.

ISO Internal Auditor Training:

This internal auditor training course introduces personnel to the business management concepts of ISO 9001:2015 and can be customized for the appropriate ISO 9001 training audience. Learn more about the Internal Auditor Training Manufacturers Based Course that IQPS offers.

IT auditor course:

A certification course for IT auditors taken to prepare for a software auditor certification exam or to maintain certification in internal audits. See our online software auditing course.

IT internal auditor:

An IT internal auditor is a professional who independently and objectively evaluates an organization’s technological information operations. Check out the IT internal auditor course that IQPS offers.

Juran trilogy:

Three managerial processes identified by Joseph M. Juran for use in managing for quality: quality planning, quality control and quality improvement.

Key performance indicator (KPI):

A statistical measure of how well an organization is doing in a particular area. A KPI could measure a company’s financial performance or how it is holding up against customer requirements.

Key process:

A major system-level process that supports the mission and satisfies major consumer requirements.

Key process characteristic:

A process parameter that can affect safety or compliance with regulations, fit, function, performance or subsequent processing of product.

Key product characteristic:

A product characteristic that can affect safety or compliance with regulations, fit, function, performance or subsequent processing of product.

Lead time:

The total time a customer must wait to receive a product after placing an order.


An essential part of a quality improvement effort. Organization leaders must establish a vision, communicate that vision to those in the organization and provide the tools and knowledge necessary to accomplish the vision.


Producing the maximum sellable products or services at the lowest operational cost while optimizing inventory levels.

Lean enterprise:

A manufacturing company organized to eliminate all unproductive effort and unnecessary investment, both on the shop floor and in office functions.

Lost customer analysis:

Analysis conducted to determine why a customer or a class of customers was lost.

Management review:

A periodic management meeting to review the status and effectiveness of the organization’s quality management system.


A standard for measurement.

Mistake proofing:

Use of production or design features to prevent the manufacture or passing downstream a nonconforming product; also known as “error proofing.”


An organization’s purpose.


The nonfulfillment of a specified requirement.

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.

Nondestructive testing and evaluation (NDT, NDE):

Testing and evaluation methods that do not damage or destroy the product being tested.


A specific statement of a desired short-term condition or achievement; includes measurable end results to be accomplished by specific teams or individuals within time limits.

Online software auditing:

A software audit is the practice of analyzing and observing a piece of software. Some types of online software auditing include reviewing software for licensing compliance, monitoring software for quality assurance, and assuring that legal requirements are being satisfied.

Operating expenses:

The money required for a system to convert inventory into throughput.

Out of spec:

A term that indicates a unit does not meet a given requirement or specification.


Products, materials, services or information provided to customers (internal or external), from a process.

Pareto chart:

A graphical tool for ranking causes from most significant to least significant. It is based on the Pareto principle, which was first defined by Joseph M. Juran in 1950. The principle, named after 19th-century economist Vilfredo Pareto, suggests most effects come from relatively few causes; that is, 80% of the effects come from 20% of the possible causes. One of the “seven tools of quality.”

Plan-do-check-act (PDCA) cycle:

A four-step process for quality improvement. In the first step (plan), a way to effect improvement is developed. In the second step (do), the plan is carried out, preferably on a small scale. In the third step (check), a study takes place between what was predicted and what was observed in the previous step. In the last step (act), action is taken on the causal system to effect the desired change. The plan-do-check-act cycle is sometimes referred to as the Shewhart cycle, because Walter A. Shewhart discussed the concept in his book Statistical Method From the Viewpoint of Quality Control, and as the Deming cycle, because W. Edwards Deming introduced the concept in Japan. The Japanese subsequently called it the Deming cycle. Also called the plan-do-study-act (PDSA) cycle.


Japanese term that means mistake-proofing. A poka-yoke device is one that prevents incorrect parts from being made or assembled or easily identifies a flaw or error.


An overarching plan (direction) for achieving an organization’s goals.

Preventive action:

Action taken to remove or improve a process to prevent potential future occurrences of a nonconformance.

Prevention cost:

The cost incurred by actions taken to prevent a nonconformance from occurring; one element of cost of quality or cost of poor quality.

Prevention versus detection:

A term used to contrast two types of quality activities. Prevention refers to activities for preventing nonconformances in products and services. Detection refers to activities for detecting nonconformances already in products and services. Another phrase to describe this distinction is “designing in quality versus inspecting in quality.”


The act of defining a problem; determining the cause of the problem; identifying, prioritizing and selecting alternatives for a solution; and implementing a solution.


The steps in a process and how these steps are to be performed for the process to fulfill a customer’s requirements; usually documented.


A set of interrelated work activities characterized by a set of specific inputs and value-added tasks that make up a procedure for a set of specific outputs.

Process control:

The method for keeping a process within boundaries; the act of minimizing the variation of a process.

Process flow diagram:

A depiction of the flow of materials through a process, including any rework or repair operations; also called a process flow chart.

Process improvement:

The application of the plan-do-check-act cycle (see listing) to processes to produce positive improvement and better meet the needs and expectations of customers.

Process improvement team:

A structured group often made up of cross-functional members who work together to improve a process or processes.

Process kaizen:

Improvements made at an individual process or in a specific area. Sometimes called “point kaizen.”

Process management:

The pertinent techniques and tools applied to a process to implement and improve process effectiveness, hold the gains and ensure process integrity in fulfilling customer requirements.

Process map:

A type of flowchart depicting the steps in a process and identifying responsibility for each step and key measures.

Process owner:

The person who coordinates the various functions and work activities at all levels of a process, has the authority or ability to make changes in the process as required and manages the entire process cycle to ensure performance effectiveness.

Process performance management (PPM):

The overseeing of process instances to ensure their quality and timeliness; can also include proactive and reactive actions to ensure a good result.

Project management:

The application of knowledge, skills, tools and techniques to a broad range of activities to meet the requirements of a particular project.

Process quality:

The value of percentage defective or of defects per hundred units in product from a given process. Note: The symbols “p” and “c” are commonly used to represent the true process average in fraction defective or defects per unit; and “l00p” and “100c” the true process average in percentage defective or in defects per hundred units.


A subjective term for which each person or sector has its own definition. In technical usage, quality can have two meanings: 1. the characteristics of a product or service that bear on its ability to satisfy stated or implied needs; 2. a product or service free of deficiencies. According to Joseph Juran, quality means “fitness for use;” according to Philip Crosby, it means “conformance to requirements.”

Quality assurance/quality control (QA/QC):

Two terms that have many interpretations because of the multiple definitions for the words “assurance” and “control.” For example, “assurance” can mean the act of giving confidence, the state of being certain or the act of making certain; “control” can mean an evaluation to indicate needed corrective responses, the act of guiding or the state of a process in which the variability is attributable to a constant system of chance causes. (For a detailed discussion on the multiple definitions, see ANSI/ISO/ASQ A3534-2, Statistics—Vocabulary and Symbols—Statistical Quality 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.

Quality audit:

A systematic, independent examination and review to determine whether quality activities and related results comply with plans and whether these plans are implemented effectively and are suitable to achieve the objectives.

Quality engineering:

The analysis of a manufacturing system at all stages to maximize the quality of the process itself and the products it produces.

Quality management (QM):

The application of a quality management system in managing a process to achieve maximum customer satisfaction at the lowest overall cost to the organization while continuing to improve the process.

Quality management system (QMS):

A formalized system that documents the structure, responsibilities and procedures required to achieve effective quality management.

Quality policy:

An organization’s general statement of its beliefs about quality, how quality will come about and its expected result.

Quality plan:

A document or set of documents that describe the standards, quality practices, resources and processes pertinent to a specific product, service or project.

Random cause:

A cause of variation due to chance and not assignable to any factor.

Random sampling:

A commonly used sampling technique in which sample units are selected so all combinations of n units under consideration have an equal chance of being selected as the sample.


The probability of a product’s performing its intended function under stated conditions without failure for a given period of time.

Risk management:

Using managerial resources to integrate risk identification, risk assessment, risk prioritization, development of risk handling strategies and mitigation of risk to acceptable levels.


The condition of a product or process design that remains relatively stable, with a minimum of variation, even though factors that influence operations or usage, such as environment and wear, are constantly changing.

Root cause:

A factor that caused a nonconformance and should be permanently eliminated through process improvement.

Root cause analysis course:

Some root cause analysis training approaches are geared more toward identifying true root causes than others; some are more general problem-solving techniques, while others simply offer support for the core activity of root cause analysis. Root cause analysis training involves learning the approach to answering a 7-step corrective action process to discover the root cause and solve the problem!

Root cause analysis training can help transform a culture that reacts to problems into a forward-looking culture that solves problems before they occur or escalate. Root cause analysis also reduces the frequency of problems occurring over time within the environment where the process is used. Take a look at our root cause analysis training course outline.

Root cause analysis:

A collective term that describes a wide range of approaches, tools and techniques used to uncover causes of problems. The root cause sets in motion the entire cause-and-effect chain causing the problem(s).


In acceptance sampling, one or more units of product (or a quantity of material) drawn from a lot for purposes of inspection to reach a decision regarding acceptance of the lot.

Sample size [n]:

The number of units in a sample.

Sample standard deviation chart (S chart):

A control chart in which the subgroup standard deviation, s, is used to evaluate the stability of the variability within a process.

Sampling at random:

As commonly used in acceptance sampling theory, the process of selecting sample units so all units under consideration have the same probability of being selected. Note: Equal probabilities are not necessary for random sampling; what is necessary is that the probability of selection be ascertainable. However, the stated properties of published sampling tables are based on the assumption of random sampling with equal probabilities. An acceptable method of random selection with equal probabilities is the use of a table of random numbers in a standard manner.

Sampling, double:

Sampling inspection in which the inspection of the first sample leads to a decision to accept a lot, reject it or take a second sample; the inspection of a second sample, when required, then leads to a decision to accept or to reject the lot.

Sampling, multiple:

Sampling inspection in which, after each sample is inspected, the decision is made to accept a lot, reject it or take another sample. But there is a prescribed maximum number of samples, after which a decision to accept or reject the lot must be reached. Note: Multiple sampling as defined here has sometimes been called “sequential n sampling” or “truncated sequential e sampling.” The term “multiple sampling” is recommended.

Sampling, single:

Sampling inspection in which the decision to accept or to reject a lot is based on the inspection of one sample.

Sampling, unit:

Sequential sampling inspection in which, after each unit is inspected, the decision is made to accept a lot, reject it or to inspect another unit.

Scatter diagram:

A graphical technique to analyze the relationship between two variables. Two sets of data are plotted on a graph, with the y-axis being used for the variable to be predicted and the x-axis being used for the variable to make the prediction. The graph will show possible relationships (although two variables might appear to be related, they might not be; those who know most about the variables must make that evaluation). One of the “seven tools of quality.”

Scientific management/approach:

A term referring to the intent to find and use the best way to perform tasks to improve quality, productivity, and efficiency of a product or service.


An evaluation device, usually in the form of a questionnaire, that specifies the criteria customers will use to rate your business’ performance in satisfying customer requirements.

Software quality assurance (SQA):

A systematic approach to evaluating the quality of and adherence to software product standards, processes and procedures. SQA includes ensuring standards and procedures are established and are followed throughout the software acquisition life cycle.


A document that states the requirements to which a given product or service must conform.

Special causes:

Causes of variation that arise because of special circumstances. They are not an inherent part of a process. Special causes are also referred to as assignable causes. Also see “common causes.”


Any individual, group or organization that will have a significant impact on or will be significantly impacted by the quality of a specific product or service.


A group of interdependent processes and people that together perform a common mission.


The metric, specification, gauge, statement, category, segment, grouping, behavior, event or physical product sample against which the outputs of a process are compared and declared acceptable or unacceptable.

Technical specification (TS):

A type of document in the International Organization for Standardization portfolio of deliverables.

Top management commitment:

Participation of the highest-level officials in their organization’s quality improvement efforts. Their participation includes establishing and serving on a quality committee, establishing quality policies and goals, deploying those goals to lower levels of the organization, providing the resources and training lower levels need to achieve the goals, participating in quality improvement teams, reviewing progress organization-wide, recognizing those who have performed well and revising the current reward system to reflect the importance of achieving the quality goals.

Total productive maintenance (TPM):

A series of methods, originally pioneered by Nippondenso (a member of the Toyota group), to ensure every machine in a production process is always able to perform its required tasks so production is never interrupted.

Total quality:

A strategic integrated system for achieving customer satisfaction that involves all managers and employees and uses quantitative methods to continuously improve an organization’s processes.

Total quality management (TQM):

A term first used to describe a management approach to quality improvement. Since then, TQM has taken on many meanings. Simply put, it is a management approach to long-term success through customer satisfaction. TQM is based on all members of an organization participating in improving processes, products, services and the culture in which they work. The methods for implementing this approach are found in the teachings of such quality leaders as Philip B. Crosby, W. Edwards Deming, Armand V. Feigenbaum, Kaoru Ishikawa and Joseph M. Juran.

Total quality control (TQC):

A system that integrates quality development, maintenance and improvement of the parts of an organization. It helps a company economically manufacture its product and deliver its services.


The act of confirming a product or service meets the requirements for which it was intended.


The ability of a feedback instrument to measure what it was intended to measure; also, the degree to which inferences derived from measurements are meaningful.


A term used to describe activities that transform input into a customer (internal or external) usable output.

Value analysis:

Analyzing the value stream to identify value-added and nonvalue added activities.

Value engineering:

Analyzing the components and process that create a product, with an emphasis on minimizing costs while maintaining standards required by the customer.

Value stream:

All activities, both value-added and non-value added, required to bring a product from raw material state into the hands of the customer, bring a customer requirement from order to delivery and bring a design from concept to launch. Also see “information flow” and “hoshin planning.”


The fundamental beliefs that drive organizational behavior and decision making.

Variable data:

Measurement information. Control charts based on variable data include average (X-bar) chart, range (R) chart, and sample standard deviation (s) chart (see individual listings).


A change in data, characteristic or function caused by one of four factors: special causes, common causes, tampering or structural variation (see individual entries).


The act of determining whether products and services conform to specific requirements.


An overarching statement of the way an organization wants to be; an ideal state of being at a future point.

Visual controls:

Any devices that help operators quickly and accurately gauge production status at a glance. Progress indicators and problem indicators help assemblers see when production is ahead, behind or on schedule. They allow everyone to instantly see the group’s performance and increase the sense of ownership in the area. Also see “andon board,” “kanban,” “production board,” “painted floor” and “shadow board.”

Vital few, useful many:

A term Joseph M. Juran used to describe the Pareto principle, which he first defined in 1950. (The principle was used much earlier in economics and inventory control methods.) The principle suggests most effects come from relatively few causes; that is, 80% of the effects come from 20% of the possible causes. The 20% of the possible causes are referred to as the “vital few;” the remaining causes are referred to as the “useful many.” When Juran first defined this principle, he referred to the remaining causes as the “trivial many,” but realizing that no problems are trivial in quality assurance, he changed it to “useful many.”

Voice of the customer:

The expressed requirements and expectations of customers relative to products or services, as documented and disseminated to the providing organization’s members.

Zero defects:

A performance standard and method Philip B. Crosby developed; states that if people commit themselves to watching details and avoiding errors, they can move closer to the goal of zero defects.