Quality Assurance Terms Glossary/D
Data - Factual information used as a basis for reasoning, discussion, or calculation; often refers to quantitative information.
Dead Messenger Society - A movie title parody that prompts recognition that organizations still tend to blame the messenger who happens to bring bad news (or call attention to the organization's problems, errors or flaws).
Deduction - An approach to theory development based on modelling.
Defect - (1) A defect is any variation of a required characteristic which is far enough removed from its target so as to cause customer dissatisfaction. (2) A product’s or service’s non-fulfilment 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; class 4 minor, is related to minor problems with respect to intended normal or reasonably foreseeable use.
Dependability - Collective term used to describe the availability performance and its influencing factors: reliability performance, maintainability performance and maintenance support performance.
Defect Opportunity - Any measurable event that provides the chance of not meeting a customer critical characteristic.
Delayed Effects - An acknowledgment of the fact that the effects of actions or decisions will likely not be fully observed in the immediate time frame. Managers need to take this into account when determining or evaluating strategies, or drawing conclusions about the effectiveness of managerial methods or actions. One of the lessons in this is that in organizations in which managers are frequently moved, it is common to incorrectly attribute the carry-over effects of the previous manager or managers to the manager currently in place, leading to erroneous conclusions about both the current and the previous manager's performance and ability.
Deming Prize - A Japanese quality award for individuals and groups that have contributed to the field of quality control.
Dependent Variables - The variable, usually the process output (y) which is affected by the independent variables (x’s).
Dependability - The degree to which a product is operable and capable of performing its required function at any randomly chosen time during its specified operating time, provided that the product is available at the start of that period. Dependability can be expressed as the ratio of time available/(time available + time required)
Design and Development - Set of processes that transforms requirements into specified characteristics or into the specification of a product, process or system.
Design Control - A set of steps focused on managing the design of a product.
Design for Disassembly - A method for developing products so that they can easily be taken apart.
Design for Maintainability - A concept that states that products should be designed in a way that makes them easy for consumers to maintain.
Design for Manufacture - The principle of designing products so that they are cost effective and easy to make.
Design for Manufacturability and Assembly - A simultaneous engineering process designed to optimize the relationship between design function, manufacturability, and ease of assembly.
Design for Remanufacture - A method for developing products so that the parts can be used in other products. Associated with green manufacturing.
Design for Reuse - Designing products so they can be used in later generations of products.
Design of Experiments - aka DOE - (1) An approach to product design that involves identifying and testing alternative inputs to the production of a product to identify the best mix of inputs. (2) A statistical experimentation approach that enables understanding of how the variables (factors) in a process contribute and interact to affect the output (response) of that process.
Design Input - The physical and performance requirements of a device that are used as a basis for device design. 
Design Intent - Starting point of comunicating with GD&T when dimensioning a part or assembly.
Design Review - (1) A formal, documented, comprehensive, and systematic examination of a design to evaluate the design requirements and the capability of the design to meet these requirements and to identify problems and propose solutions. (2) A documented, comprehensive, systematic examination of a design to evaluate the adequacy of the design requirements, to evaluate the capability of the design to meet these requirements, and to identify problems.
Design Validation - Testing to ensure that product conforms to defined user needs and/or requirements. Design validation follows successful design verification and is normally performed on the final product under defined operating conditions. Multiple validations may be performed if there are different intended uses. Also, establishing by objective evidence that device specifications conform with user needs and intended use(s).
Design Verification - Review of standards, requirements and other factors to ensure that all design outputs meet design input requirements. Design verification may include activities such as: 1. Design Review 2. Performing Alternate Calculations 3. Understanding Tests and Demonstrations 4. Review of Design Stage Documents before release
Detection - The process of inspection or looking for defects after the output has been produced. Often compared to “prevention” in which the process is improved to avoid making the defect.
Development Plan - A plan that identifies the skills that will be required for a particular employee to move up in an organization.
Deviation - An authorization by a customer to depart from specified requirements for a specified quantity or for a specified period of time.
Deviation Permit - Written authorization, prior to production or provision of a service, to depart from specified requirements for a specified quantity or for a specified time.
Devil's Advocate - Reference to the role assumed by a person who takes the opposing side in a discussion in order to provide a good "test" of the prevailing argument (even though that person may not be personally opposed).
DFA - Design for Assembly
DFM - Design for Manufacturability. Design of product that considers the capability of the manufacturing process and the robustness of the product design to "forgive" (tolerate without affecting quality) process variation.
DFMEA - Design failure mode and effects analysis
Diagnostic Journey and Remedial Journey - A two phase investigation used by teams to solve chronic quality problems. In the first phase, diagnostic journey, the team journeys from the symptom of a chronic problem to its cause. In the second phase, remedial journey, the team journeys from the cause to its remedy.
Discrete Data - Data that can only be described by levels, i.e. Pass/fail, colour. Discrete data cannot be logically subdivided.
Discrete Variable - A quantitative variable whose set of possible values is countable. A random variable is discrete if and only if its cumulative probability distribution function is a stair-step function; i.e., If it is piecewise constant and only increases by jumps.
Distance Learning - Training that is conducted in one location and is observed in a distant location through telecommunications technology.
Distribution - The population (universe) from which observations are drawn, categorized into cells, and form identifiable patterns. It is based on the concept of variation that states that anything measured repeatedly will arrive at different results. These results will fall into statistically predictable patterns. A bell-shaped curve (normal distribution) is an example of a distribution in which the greatest number of observations occur in the center with fewer and fewer observations falling evenly on either side of the average.
DMAIC - Define, Measure, Analyze, Improve, Control.
Dodge-Romig Sampling Plans - Plans for acceptance sampling involving four sets of tables: single-sampling lot tolerance tables, double-sampling lot tolerance tables, single-sampling average outgoing quality limit tables, and double-sampling average outgoing quality limit tables.
DPMO - Defects Per Million Opportunities.
Dual Sourcing - Using only a few suppliers for a single component.
Durability - (1) A dimension of quality that refers to a product’s ability to withstand stress or trauma. (2) The probability that an item will continue to function at customer expectation levels, at the useful life without requiring overhaul or rebuild due to wearout.