R

Random Selecting a sample so each item in the population has an equal chance of being selected; lack of predictability; without pattern.

Random Sample One or more samples randomly selected from the universe (population).

Random Sampling The process of selecting units for a sample of size, so that all units have an equal chance of being selected as the sample.

Random Variable A variable which can assume any value from a set of possible values.

Random Variations Variations in data which result from causes which cannot be pinpointed or controlled.

Range The difference between the highest and lowest values in a set of values or "subgroup."

Range Control Chart Control chart in which the range of the subgroup is used to track the instantaneous variation within a process, i.e. the variation in the process at any one time, when many input factors would not have time to vary enough to make a detectable difference. Range charts are usually paired with average charts for complete analysis.

Ranks Values assigned to items in a sample to determine their relative occurrence in a population.

Record. (1) (ISO) a group of related data elements treated as a unit. [A data element (field) is a component of a record, a record is a component of a file (database)].

Registered Suppliers Registered Suppliers are suppliers who have received third party registration to a specific quality system standard for the commodity supplied.

Regrade Action taken on non-conforming product that changes the classification, or category of the product for use in alternative applications. Cannot be done without customer approval/direction. [Also see Repair/Rework]

Regression analysis A statistical technique used to determine the best mathematical expression to describe the relationship between a response and independent variables.

Regression analysis and testing. (IEEE) A software V&V task to determine the extent of V&V analysis and testing that must be repeated when changes are made to any previously examined software products. See: testing, regression.

Relations Diagram method is a technique developed to clarify intertwined causal relationships in a complex situation in order to find an appropriate solution. It is typically represented graphically as squared ellipses (concepts) connected by directed lines (arrowheads show direction). The directed lines represent causal relations between the concepts.

Release. (IEEE) The formal notification and distribution of an approved version. See: version.

Reliability assessment. (ANSI/IEEE) The process of determining the achieved level of reliability for an existing system or system component.

Reliability The probability of a product or service successfully doing its job under given conditions.

Reliability The probability that an item will continue to function at customer expectation levels at a measurement point, under specified environmental and duty cycle conditions.

Reliability. (IEEE) The ability of a system or component to perform its required functions under stated conditions for a specified period of time. See: software reliability.

Repair Action taken on non-conforming product so that the product will fulfill the intended usage, although the product may not
conform to the original requirements. [Also see Regrade/Rework]

Replication Observations made under identical test conditions.

Representative Sample A sample which accurately reflects a specific condition or set of conditions within the universe.

Requirement. (IEEE) (1) A condition or capability needed by a user to solve a problem or achieve an objective (2) A condition or capability that must be met or possessed by a system or system component to satisfy a contract, standard. specification, or other formally imposed documents. (3) A documented representation of a condition or capability as in (1) or (2). See: design requirement, functional requirement, implementation requirement, interface requirement, performance requirement, physical requirement.

Requirements analysis. (IEEE) (1) The process of studying user needs to arrive at a definition of a system, hardware, or software requirements. (2) The process of studying and refining system, hardware, or software requirements. See: prototyping, software engineering.

Requirements phase. (IEEE) The period of time in the software life cycle during which the requirements, such as functional and performance capabilities for a software product, are defined and documented.

Resources-those items necessary for a team to understand a problem and implement solutions; also, the time to work on solutions, access to manufacturing engineers, etc.
revalidation. Relative to software changes, revalidation means validating the change itself, assessing the nature of the change to determine potential ripple effects, and performing the necessary regression testing.

Review. (IEEE) A process or meeting during which a work product or set of work products, is presented to project personnel, managers, users, customers, or other interested parties for comment or approval. Types include code review, design review, formal qualification review, requirements review, test readiness review. Contrast with audit, inspection. See: static analysis.

Rework Action taken on non-conforming product so that it will meet the specified requirements.

RFP Request For Proposal

RFQ Request For Quotation

Risk assessment. (DOD) A comprehensive evaluation of the risk and its associated impact.

Risk The possibility of loss, injury, disadvantage or destruction. Apply this definition to the issues of program management and you have the starting point for successful risk management

Risk. (IEEE) A measure of the probability and severity of undesired effects. Often taken as the simple product of probability and consequence.

Robust design An approach to the planning of new products and services that harnesses Taguchi methods.

Robust The ability of a product or service to function appropriately regardless of external conditions and other uncontrollable factors.

Root Cause Analysis Using one or more various tools to determine the root cause of a specific failure.

Root Cause The lowest level cause of a failure, or variation in a product, component, or process .

RPN Risk Priority Number (ref: FMEA)

Run 1) SPC: A consecutive number of points consistently increasing or decreasing. 2) Production: The production of a specified number of sequential units.

Run chart Also known as a line chart, or line graph. A chart that plots data over time, allowing you to identify trends and anomalies.