CQE key terms

An organization-wide approach in which every function continuously improves quality by focusing on customer requirements, employee involvement, data-based decisions, and long-term management commitment rather than relying on inspection alone.

The total money spent on prevention, appraisal, and the costs of internal and external failures, used to show how investment in prevention and appraisal reduces failure spending over time.

Comparing an organization's processes, products, or performance measures against recognized leaders or documented best practices in order to identify gaps and set realistic improvement targets.

A short formal statement from top management declaring the organization's commitment to quality, its guiding principles, and the framework within which quality objectives are set and reviewed.

The coordinated set of documented processes, responsibilities, resources, and records an organization uses to direct and control quality so customer, statutory, and regulatory requirements are consistently met.

An international standard that specifies requirements for a quality management system, built on the process approach, risk-based thinking, and continual improvement; organizations may be certified to it by an accredited body.

A systematic, independent, and documented examination of processes or of an entire quality system against specified criteria such as a standard, contract, or internal procedure, producing findings and improvement opportunities.

A structured process for eliminating the cause of an existing nonconformity (corrective action) or of a potential one (preventive action), including root cause analysis, implementation, and verification that the action worked.

The evaluation and approval of a supplier's capability through audits, sample evaluation, certifications, or performance history, done before and during purchasing to ensure purchased materials consistently meet requirements.

A planning method that translates customer needs, gathered as the voice of the customer, into prioritized design requirements and process specifications, typically displayed in a matrix called the house of quality.

Verification confirms that design outputs meet the specified design inputs; validation confirms that the finished product or service actually meets customer needs under real conditions of use.

Reliability is the probability that an item performs its required function for a stated period under stated conditions; mean time between failures is the average operating time between failures for repairable items.

A design approach that makes product or process performance insensitive to noise factors such as environment, raw material, or operator, often by selecting factor settings that maximize a signal-to-noise ratio.

A visual map showing the sequence of steps, inputs, outputs, and decision points in a process, used to expose complexity, non-value-added steps, and places where errors can be introduced.

A time-ordered plot of a process statistic with statistically calculated control limits; points beyond the limits or in nonrandom patterns signal special-cause variation that requires investigation.

The use of statistical techniques, mainly control charts, to monitor a process in real time, distinguish common from special causes, and reduce variation so the process stays stable and capable.

Deciding to accept or reject a lot by inspecting a sample drawn from it rather than every unit, using a plan that defines the sample size and the acceptance and rejection numbers.

A graph that shows, for a given sampling plan, the probability of accepting a lot as a function of the lot's true quality level, making producer and consumer risk visible.

The quality level in a sampling plan that is treated as acceptable as a process average; lots at this level have a high, though not guaranteed, probability of being accepted.

A document listing process steps, product and process characteristics, specifications, measurement methods, sample sizes, frequencies, and reaction plans used to keep a process in control.

An error-proofing device or design feature that prevents a mistake from being made or makes it immediately obvious, so defects cannot be created or passed to the next step.

Product that does not meet requirements is identified and segregated, and a material review board decides whether to rework, repair, use as is, or scrap it, documenting the disposition taken.

Comparing an instrument's readings with a reference standard of known accuracy and adjusting or documenting the result, so that measurements remain traceable, consistent, and fit for their purpose.

A repeating improvement cycle: plan a change and the measures for it, do it on a small scale, check results against the plan, and act by standardizing the gain or adjusting before the next cycle.

The Six Sigma project sequence of define, measure, analyze, improve, and control, used to solve existing problems by finding root causes with data and then locking in the gains.

A lean tool that diagrams the material and information flow for a product family, marking value-added and non-value-added time, to reveal where lead time and waste can be reduced.

Ongoing small-step improvement carried out by the people who do the work, often through focused team events that remove waste in a specific area rather than relying on large capital projects.

A workplace organization method with five steps: sort, set in order, shine, standardize, and sustain; it removes clutter and makes abnormal conditions, such as missing or misplaced items, easy to see.

Indices that compare the spread of a stable process with its specification limits; Cp ignores centering while Cpk accounts for how far the process mean sits from the nearer specification limit.

A study of how much observed measurement variation comes from the gauge, the appraisers, and their interaction (repeatability and reproducibility) compared with real part-to-part differences, before data are trusted.

A planned set of runs in which factors are deliberately varied together so that their individual effects and interactions on a response can be estimated efficiently and with known confidence.

A procedure that uses sample data to choose between a null hypothesis and an alternative; a Type I error rejects a true null, while a Type II error fails to reject a false null.

A statistical method that splits total variation in data into components attributed to different sources, such as factors or treatment groups, and tests whether group means differ significantly.

A method for modeling the relationship between a response variable and one or more predictor variables, used to estimate effects, predict values, and judge how much variation is explained.

A ranking of problem categories by frequency or cost that usually shows a few causes produce most of the effect, helping teams focus improvement effort on the highest-payback items first.

The core graphical problem-solving set: process flow chart, check sheet, histogram, Pareto chart, cause-and-effect (fishbone) diagram, scatter diagram, and control chart, used to organize and interpret data.

A team-based method that lists potential failure modes for a product or process, rates their severity, occurrence, and detection, and prioritizes actions to reduce the highest risks first.

In FMEA, the product of the severity, occurrence, and detection ratings, each usually scored from one to ten, used to rank failure modes so attention goes to the largest concerns.

A top-down deductive diagram that begins with an undesired top event and traces, through logic gates such as AND and OR, the combinations of lower-level failures that could cause it.

The practice of identifying, weighing, and addressing risks and opportunities across processes so that the effort and controls applied are proportional to the chance and impact of failure.