American Society for Testing and Materials (ASTM): Not-for-profit organization that provides a forum for the development and publication of voluntary consensus standards for materials, products, systems and services.
Analysis of means (ANOM): A statistical procedure for troubleshooting industrial processes and analyzing the results of experimental designs with factors at fixed levels. It provides a graphical display of data. Ellis R. Ott developed the procedure in 1967 because he observed that nonstatisticians had difficulty understanding analysis of variance. Analysis of means is easier for quality practitioners to use because it is an extension of the control chart. In 1973, Edward G. Schilling further extended the concept, enabling analysis of means to be used with non-normal distributions and attributes data in which the normal approximation to the binomial distribution does not apply. This is referred to as analysis of means for treatment effects.
Analysis of variance (ANOVA): A basic statistical technique for determining the proportion of influence a factor or set of factors has on total variation. It subdivides the total variation of a data set into meaningful component parts associated with specific sources of variation to test a hypothesis on the parameters of the model or to estimate variance components. There are three models: fixed, random and mixed.
Appraisal cost: The cost of ensuring an organization is continually striving to conform to customers’ quality requirements.
Arrow diagram: A planning tool to diagram a sequence of events or activities (nodes) and their interconnectivity. It is used for scheduling and especially for determining the critical path through nodes.
Assessment: A systematic evaluation process of collecting and analyzing data to determine the current, historical or projected compliance of an organization to a standard
Assignable cause: A name for the source of variation in a process that is not due to chance and therefore can be identified and eliminated. Also called “special cause.”
Assn. for Quality and Participation (AQP): Was an independent organization until 2004, when it became an affiliate organization of ASQ. Continues today as ASQ’s Team and Workplace Excellence Forum
Attribute data: Go/no-go information. The control charts based on attribute data include percent chart, number of affected units chart, count chart, count per unit chart, quality score chart and demerit chart
Attributes, method of: A method of measuring quality that consists of noting the presence (or absence) of some characteristic (attribute) in each of the units under consideration and counting how many units do (or do not) possess it. Example: go/no-go gauging of a dimension.
Audit: 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
Automotive Industry Action Group (AIAG): A global automotive trade association with about 2,600-plus member companies that focuses on common business processes, implementation guidelines, education and training.
Average chart: A control chart in which the subgroup average, X-bar, is used to evaluate the stability of the process level.
Average outgoing quality (AOQ): The expected average quality level of an outgoing product for a given value of incoming product quality.
Average outgoing quality limit (AOQL): The maximum average outgoing quality over all possible levels of incoming quality for a given acceptance sampling plan and disposal specification.
Average run lengths (ARL): On a control chart, the number of subgroups expected to be inspected before a shift in magnitude takes place.
Average sample number (ASN): The average number of sample units inspected per lot when reaching decisions to accept or reject.
Average total inspection (ATI): The average number of units inspected per lot, including all units in rejected lots (applicable when the procedure calls for 100% inspection of rejected lots).
Balanced scorecard: A management system that provides feedback on internal business processes and external outcomes to continuously improve strategic performance and results.
Balancing the line: The process of evenly distributing the quantity and variety of work across available work time, avoiding overburden and underuse of resources. This eliminates bottlenecks and downtime, which translates into shorter flow time.
Calibration: The comparison of a measurement instrument or system of unverified accuracy to a measurement instrument or system of known accuracy to detect any variation from the required performance specification.
Capacity constraint resources: A series of non-bottlenecks (based on the sequence in which jobs are performed) that can act as a constraint.
Characteristic: The factors, elements or measures that define and differentiate a process, function, product, service or other entity.
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).
Classification of defects: The listing of possible defects of a unit, classified according to their seriousness. Note: Commonly used classifications: class A, class B, class C, class D; or critical, major, minor and incidental; or critical, major and minor. Definitions of these classifications require careful preparation and tailoring to the product(s) being sampled to ensure accurate assignment of a defect to the proper classification. A separate acceptance sampling plan is generally applied to each class of defects.
Cp: The ratio of tolerance to 6 sigma, or the upper specification limit (USL) minus the lower specification limit (LSL) divided by 6 sigma. It is sometimes referred to as the engineering tolerance divided by the natural tolerance and is only a measure of dispersion.
Cpk index: Equals the lesser of the USL minus the mean divided by 3 sigma (or the mean) minus the LSL divided by 3 sigma. The greater the Cpk value, the better.
Defect: A product’s or service’s nonfulfillment of an intended requirement or reasonable expectation for use, including safety considerations. There are four classes of defects: class 1, very serious, leads directly to severe injury or catastrophic economic loss; class 2, serious, leads directly to significant injury or significant economic loss; class 3, major, is related to major problems with respect to intended normal or reasonably foreseeable use; and class 4, minor, is related to minor problems with respect to intended normal or reasonably foreseeable use. Also see “blemish,” “imperfection” and “nonconformity.”
Defective: A defective unit; a unit of product that contains one or more defects with respect to the quality characteristic(s) under consideration.
Failure: The inability of an item, product or service to perform required functions on demand due to one or more defects.
Inspection lot: A collection of similar units or a specific quantity of similar material offered for inspection and acceptance at one time.
Inspection, normal: Inspection used in accordance with a sampling plan under ordinary circumstances.
Inspection, reduced: Inspection in accordance with a sampling plan requiring smaller sample sizes than those used in normal inspection. Reduced inspection is used in some inspection systems as an economy measure when the level of submitted quality is sufficiently good and other stated conditions apply. Note: The criteria for determining when quality is “sufficiently good” must be defined in objective terms for any given inspection system.
Inspection, tightened: Inspection in accordance with a sampling plan that has stricter acceptance criteria than those used in normal inspection. Tightened inspection is used in some inspection systems as a protective measure when the level of submitted quality is sufficiently poor. The higher rate of rejections is expected to lead suppliers to improve the quality of submitted product. Note: The criteria for determining when quality is “sufficiently poor” must be defined in objective terms for any given inspection system.
Prevention cost: The cost incurred by actions taken to prevent a nonconformance from occurring; one element of cost of 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.
Preventive action: Action taken to prevent occurrence of nonconformances.
Reliability: The probability of a product performing its intended function under stated conditions without failure for a given period of time.
Root cause: A factor that caused a nonconformance and should be addressed with corrective action.
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, single: Sampling inspection in which the decision to accept or reject a lot is based on the inspection of one sample.
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 reject the lot.
Statistical process control (SPC): The application of statistical techniques to control a process; often used interchangeably with the term “statistical quality control” (see listing).
Statistical quality control (SQC): The application of statistical techniques to control quality. Often used interchangeably with the term “statistical process control” (see listing), although statistical quality control includes acceptance sampling, which statistical process control does not.
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).
Variation: A change in data, characteristic or function caused by one of four factors: special causes, common causes, tampering or structural variation (see individual entries).
