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Quality Glossary - R


RAM: Reliability/availability/maintainability (see individual entries).

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.

Range (statistical): The measure of dispersion in a data set (the difference between the highest and lowest values).

Range chart (R chart): A control chart in which the subgroup range, R, evaluates the stability of the variability within a process.

New! Recall: The act of officially summoning someone or something back to its place of origin.

Red bead experiment: An exercise developed by W. Edwards Deming to illustrate that results are largely dependent on the management system—which is owned by top management—and not the employees who work in the system

Re-engineering: A process for restructuring an entire organization and its processes.

Registrar: Generally accepted equivalent term for “certification body.”

Registration: The act of including an organization, product, service or process in a compilation of those having the same or similar attributes.

Registration to standards: A process in which an accredited, independent third-party organization conducts an on-site audit of an organization's operations against the requirements of the standard to which the organization wants to be registered. Upon successful completion of the audit, the organization receives a certificate indicating it has met the standard requirements. In countries outside the United States, this generally is known as certification.

Regression analysis: A statistical technique for determining the best mathematical expression describing the functional relationship between one response and one or more independent variables.

Rejection number: The smallest number of defectives (or defects) in the sample or samples under consideration that will require rejection of the lot.

Relations diagram: See "interrelations diagram."

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

Repeatability: The variation in measurements obtained when one measurement device is used several times by the same person to measure the same characteristic on the same product.

Reproducibility: The variation in measurements made by different people using the same measuring device to measure the same characteristic on the same product.

Requirements: A need or expectation, generally mandatory or compulsory.

Resource utilization: Using a resource in a way that increases throughput.

Results: Outcomes that can be qualitative or quantitative.

Right size: Matching tooling and equipment to the job and space requirements of lean production. Right sizing is a process that challenges the complexity of equipment by examining how equipment fits into an overall vision for workflow through a factory. When possible, right sizing favors smaller, dedicated machines rather than large, multipurpose batch processing ones.

Right the first time: Meeting specified requirements with the initial attempt.

Risk management: The identification, evaluation and prioritization of risks to eliminate or mitigate their probability or severity or to leverage opportunities.

Robustness: 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 addressed with corrective action.

New! Root cause analysis: The method of identifying the cause of a problem, solving it and preventing it from occurring again. Uncovering the correct and accurate reason(s) why something is happening or has already occurred.

Run chart: A chart showing a line connecting numerous data points collected from a process running over time.

Runner: A person on the production floor who paces the entire value stream through the pickup and delivery of materials through kanban (see listing) usage.