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Glossary of Quality-Related Terms

This glossary includes terms commonly used in the context of EPA's Quality System. These definitions were adapted from EPA or other federal publications; reprinted with permission from the American Society for Quality (ASQ); or included at the suggestion of the EPA QA Community.

These definitions do not constitute the Agency's official use of terms and phrases for regulatory purposes, and nothing in this document should be construed to alter or supplant any other federal document. Official terminology may be found in the laws and related regulations as published in such sources as the Congressional Record, Federal Register, and elsewhere.
 
[1] Reprinted with permission from the Quality Progress.
© 2002 American Society for Quality.
ASQ definitions may be found also at:
http://www.asq.org/pub/qualityprogress/ Exit Disclaimer
http://www.asq.org/sixsigma/terms/index.html Exit Disclaimer
Siebels, Donald L. The Quality Improvement Glossary. 2004. Quality Press. Milwaukee, WI.
 
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Acceptable Quality Level (AQL)
  The maximum number of errors, defects, or contamination at which data are considered usable.
 
Acceptance Criteria
  Specific limits placed on the characteristic of an item, process, or service, as defined in a requirements document, to be considered satisfactory for use. See also Performance Criteria.
 
Accreditation
 

The process by which an agency or organization evaluates and recognizes a laboratory as meeting certain predetermined qualifications or standards, thereby accrediting the laboratory.

Certification by a duly recognized body of the facilities, capability, objectivity, competence and integrity of an agency, service, or operational group or individual to provide the specific service or operation needed.[1]

 
Accuracy
  The closeness or agreement of the observed value or test response to the true or acceptable reference value or the test response from a reference method. It is influenced by both random error (precision) and systematic error (bias). The terms “bias” and “precision” are often used in lieu of “accuracy”.
Action Level
  The numerical value that causes the decision maker to choose one of the alternative decisions (e.g., conformity or nonconformity). This may be a regulatory threshold standard, such as a maximum contaminant level; a risk-based concentration level; a technology limitation; or a reference-based standard.
 
Analysis of Variance (ANOVA)
  A statistical method for making comparisons between two or more groups by evaluating the differences within and between data sets to assess the sources.

A basic statistical technique for analyzing experimental data. It subdivides the total variation of a data set into meaningful component parts associated with specific sources of variation in order to test a hypothesis on the parameters of the model or to estimate variance components. There are three models: fixed, random and mixed.[1]

 
Assessment
  A general evaluation process used to evaluate the performance, effectiveness and processes of a management and/or technical system, e.g., peer review, surveillance, and audits.

A systematic process of collecting and analyzing data to determine the current, historical or projected status of an organization.[1]

Audit (quality)
  A systematic and independent examination to determine whether operational activities or processes conform to planned arrangements, e.g., policy requirements, regulations, etc., and are being implemented effectively and suitably to achieve objectives.
 
Audit Criteria
  The defined policies, procedures, and requirements selected as reference values to evaluate a system or process.
 
Audit Findings
  The results of an evaluation, often designated in a written report as either nonconformances (departure from or absence of a specified requirement) or areas of concern (items that should be evaluated for preventative action or quality improvement); observations to required criteria.
 
Auditor
  A person who performs an audit.
Auditor, Certified or Qualified
  An individual who has been trained and tested to conduct audits under specific criteria or standards.
 
Audit Scope
The nature and extent of activities to be covered in an audit.
 
Background Sample
  A specimen taken that is devoid of contamination, influence or interference from the subject or area of study.
 
Baseline Condition
  A standard or situation that is used as a basis for comparison or as a starting point for further development.
Batch or Lot
  The collection of samples of the same group which is to be analyzed in one test run or inspected together within a specific time limit and traceable as a unit; also a set of data or jobs to be processed in one computer run.
Bias
  The constant or systematic distortion of a measurement process, different from random error, which manifests itself as a persistent positive or negative deviation from the known or true value. This can result from improper data collection, poorly calibrated analytical or sampling equipment, or limitations or errors in analytical methods and techniques.
 
Biased Sampling
  A collection scheme based on a very limited or prejudiced non-random collection of specimens.
 
Bimodal Distribution
  A statistical frequency of occurrence having two separate peaks or modes.
Blank / Blank Sample
  A specimen that is intended to contain none of the analytes of interest and which is subjected to the usual analytical or measurement process to establish a zero baseline or background value. Some examples are trip, bottle, equipment, instrument, reagent, and method blanks.
 
Blind Sample
  A specimen submitted for analysis with a composition and identity known to the submitter but not to the analyst.
 
Boundaries
  The spatial and temporal conditions and practical constraints under which the study is conducted or data collected.
 
Boundary Condition
A mathematical expression or set of restriction situations specifying the upper and lower limits for an element or model.
Calibration
  A comparison of a measurement standard, instrument, or item with one having higher accuracy to detect, quantify, and record any inaccuracy or variation; the process by which an instrument setting is adjusted based on response to a standard to eliminate the inaccuracy.

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.[1]

 
Calibration Drift
  The deviation in instrument response from its set or reference value over a period of time.
 
Calibration Standards
  Reference solutions of known value used to correct an instrument reading.
 
Certification
  The process of testing and evaluation against specifications which are designed to document, verify, and recognize the competence of a person, organization, or other entity to perform a function or service, usually for a specified time.

The result of meeting the established criteria set by an accrediting or certificate granting organization.[1]

Chain-of-Custody (COC)
 

An unbroken trail of accountability that ensures the physical security of samples, data, and records.

 
Characteristic
  Any property or attribute of a datum, item, process, or service that is distinct, describable, and/or measurable.

The factors, elements or measures that define and differentiate a process, function, product, service or other entity.[1]

 
Coefficient of Variation (CV)
  The standard deviation divided by the mean; a unit-free measure of variability. Also known as Relative Standard Deviation.
 
Collaborative Test
  An evaluation of a new method or process, or a component of that process, by a multitude of laboratories following the same procedures and testing the same number of similar samples.
Comparability
  A measure of the confidence with which one data set, element, or method can be considered as similar to another, e.g., taken from the same location, taken in a similar manner, etc.
 
Compatibility
  The capability in which one data set can be reconciled or integrated with another, often expressed as a statistical measure.
 
Completeness
  A measure of the amount of valid data obtained from a measurement system as compared to the planned amount, usually expressed as a percentage; also a measure of the degree to which the sampling scheme represents the available range in something, regardless of what was planned.
 
Compliance
  The act of meeting all regulations, observing requirements, or meeting set standards or demands. Also known as conformance.

The state of an organization that meets prescribed specifications, contract terms, regulations or standards.[1]
Composite Sample
  A specimen composed of several individual subsections of a population taken at different locations at a site, generally of the same size or volume, and then completely mixed.
 
Composite Sampling
  The method by which several samples are collected and then physically mixed into one larger sample.
 
Computer Model/ Modeling
  A representation or simulation of a planned or existing system using data from that system or one similar to it; the use of historical data or the modification of that data to mathematically determine the possibility of affects on the current situation or to predict future affects.
 
Computer Program Verification
  The process of evaluating whether a mathematical or statistical model has the capability to function as intended and can meet all specified requirements.
Computer Software
  The programs, written routines, and instructions that control or run the functioning of the hardware and direct its operations, e.g., systems software and applications software.
 
Computer Software Validation
  An evaluation process to determine that the programs, written routines, and instructions conform to specified requirements, usually performed by an independent party.
 
Conceptual Model
  An interpretation or working description of the characteristics of a physical system, such as a description of the expected source of the contaminant and the size and breadth of the area of concern, including relevant fate and transport pathways and potential exposure pathways.
 
Confidential Business Information (CBI)
  Information, in any form, received by the U.S. Environmental Protection Agency from a person, firm, partnership, corporation, association, or local, State, or Federal agency that relates to trade secrets or commercial or financial information and that has been claimed as confidential by the person submitting it under the procedures in Code of Federal Regulations.
Confidence Interval (C.I.)
  A range estimate of a population parameter combined with a known probability.
 
Confidence Level
  A measure of the degree of reliability, e.g., the higher the confidence level, the lower the risk of not including the parameter.
 
Conformity
  An affirmative indication or judgment that a product or service has met the requirements of the relevant specification, contract, or regulation; also, the state of meeting requirements.
 
Consensus Standard
  A rule or requirement established by a group representing a cross section of a particular industry or trade, or a part thereof.
Contaminant(s) of Concern
  The matrix-specific list of chemical or biological compounds and analytes determined to be pertinent to a specific site or project.
 
Control Chart
  A graphic representation of the variability in a measurement process generally plotted in order over time.

A chart with upper and lower control limits on which values of some statistical measure for a series of samples or subgroups are plotted.

 
Control Limits
  The variation in a process data set expressed as plus/minus standard deviations from the mean, generally placed on a chart to indicate the upper and lower acceptable ranges of process data and to judge whether the process is in or out of statistical limitations.

The natural boundaries of a process within specified confidence levels, expressed as the upper control limit (UCL) and the lower control limit (LCL).[1]
 
Corrective Action
  Any measures taken to rectify conditions adverse to quality and/or to eliminate the causes of an existing nonconformity, defect, or other undesirable situation in order to prevent reoccurrence.
Corrective Action Plan
  A scheme for amending a measurement or management process.
 
Correlation (statistical)
  A measure of the strength of the relationship between two variables. Pearson’s (or ordinary) correlation uses actual values; Spearman’s rank correlation uses the relative ranks of the observations.

A measure of the relationship between two data sets of variables.[1]
 
Cost Of Quality
  The expenditure of resources (financial, personnel, and time) to ensure the acceptability and soundness, (i.e., the quality) of a product or process to meet the customer’s needs; often contrasted with the cost of poor quality/nonconformance such as rework or inadvertent release of questionable products.
 
Criteria
  The standards, requirements, or expectations upon which an activity, such as a project, process, or method, can be evaluated and a decision made.
Customer Specifications
The descriptions of what the client/data user wants from the process.
 
Data Analysis
  The review of facts and application of statistical processes to describe, summarize, and identify data patterns and significance.
 
Data Collection Design
  The configuration plan of an environmental monitoring effort to satisfy planning requirements (e.g. DQOs).
 
Data Deliverables
  Field and/or analytical reports supplied to the customer in order to satisfy a contract or project requirement.
Data Flow
  The movement of facts in a process or computer system.
 
Data Integrity
  The maintenance of the validity of the recorded information from accidental or malicious modification or destruction; the accuracy, consistency, correctness, and soundness of a body of information. See also information integrity.
 
Data Mining
  A search through databases (secondary or pre-existing information sets) to discover and identify patterns or trends or for use in a new project.
Data Processing
  The organization and manipulation of information.
 
Data Quality
  A measure of the degree of acceptability or utility of information for its intended use.
 
Data Quality Assessment (DQA)
  A statistical and scientific evaluation of an operation’s information to determine if the information is of the right type, quality, and quantity to support their intended use.
 
Data Quality Indicators (DQIs)
  The quantitative statistics and qualitative descriptors that are used to interpret the degree of acceptability or utility of information to the user. The principal DQIs are precision, bias, representativeness, comparability, completeness, and sensitivity.
Data Quality Objectives (DQOs)
  Qualitative and quantitative statements derived from the DQO Planning Process that clarify the purpose of the study, define the most appropriate type of information to collect, determine the most appropriate conditions from which to collect that information, and specify tolerable levels of potential decision errors.
 
Data Quality Objectives Planning Process
  A systematic strategic development tool based on the scientific method that identifies and defines the type, quality, and quantity of information needed to satisfy a specified use.
 
Data Reduction
  The process of transforming unprocessed information items by arithmetic or statistical calculations, standard curves, and concentration factors, and collating them into a more useful form.
 
Data Review
  The process of examining and/or evaluating the collected information to varying levels of detail and specificity and which includes verification, validation, and usability assessment.
Data Usability
  A determination process where the information collected is evaluated as to whether it is satisfactory and acceptable for the customer’s intended use.
 
Data Validation
  An analyte- and sample-specific process that evaluates the information after the verification process (i.e., determination of method, procedural, or contractual compliance) to determine analytical quality and any limitations.
 
Data Verification
  The process of evaluating the completeness, correctness, and conformance/compliance of a specific information set against the method, procedural, or contractual specifications for that activity.
 
Data Warehouse
  An electronic repository where information is storage, analyzed, managed, maintained for analysis and future use. If access is allowed and the system properly maintained, the subject of the information and associated metrics will allow future users to determine the usability of that information for their needs.
Decision Error
  A mistake made when the data presented misleads a data user into choosing the wrong response action, in the sense that a different action would have been taken if the data user had access to unlimited “perfect” information or absolute truth.
 
Decision Maker
  The individual, or organization, which will use the collected data to make a judgment.
 
Defensible
  The ability to withstand any reasonable challenge related to the veracity or integrity of project documents, the data, and the derived information.
 
Deficiency
  An unauthorized deviation from acceptable procedures or practices, or a defect in an item that may render it as unacceptable or indeterminate; nonfulfillment of a specification or standard.
Descriptive Statistics
  Simple mathematical probability expressions that use various techniques to denote quantitative data such as graphs, diagrams, and basic data identifiers such as mean, variance, range, median, standard deviation, etc.
 
Design
  Specifications, drawings, process criteria, and performance requirements; also the results of deliberate planning and analysis, mathematical manipulations.
 
Design of Experiments (DOE)
  The systematic plan for the controlled testing of a hypothesis through experimentation so that the data produced will provide the needed information.

A branch of applied statistics dealing with planning, conducting, analyzing and interpreting controlled tests to evaluate the factors that control the value of a parameter or group of parameters.[1]
 
Detection Level
  The lowest “measurable” analyte concentration by a specified method.
Detection Limit
  The lowest concentration or amount of the target analyte that can be determined to be different from zero by a single measurement at a stated level of probability.
 
Deviation
  An abnormality or a departure from what is required or expected.

In numerical data sets, the difference or distance of an individual observation or data value from the center point (often the mean) of the set distribution.[1]
 
Dispersion
  The degree of “data scatter” (random disposition) around the data mean or median.
 
Distribution
  The concentration of an element at a point over time, over an area, or within a volume; a probability function (density function, mass function, distribution function) used to describe a set of observations (statistical sample) or a population from which the observations are generated.
Document Control
The policies and procedures used by an organization to ensure that its written activities and reports, and their revisions, are reviewed, approved for release, inventoried, distributed, archived, stored, and retrieved in accordance with the organization’s requirements.
 
Environmental Conditions
  The description of a physical medium (e.g., air, water, soil, or sediment) or biological system expressed in terms of its physical, chemical, radiological, or biological characteristics.
 
Environmental Data
  Any measurements or information that describe natural processes, locations, or conditions; ecological or health effects and consequences; or the performance of technology dealing with natural process; and, for EPA, information collected directly from measurements, produced from models, and compiled from other sources such as mathematical repositories or the literature.
 
Environmental Data Operation
  Work performed to obtain, use, or report information pertaining to natural surroundings and conditions.
Environmental Monitoring
  The process of measuring or collecting information on natural surroundings.
 
Environmental Processes
  Any manufactured or natural events that produce discharges to, or that impact, the natural state.
 
Environmental Programs
  An all-inclusive term pertaining to any work or activities involving the natural ecological condition, including but not limited to: characterization of processes and conditions; monitoring; research and development; the design, construction, and operation of technologies; and laboratory operations on samples.
 
Environmental Technology
  An all-inclusive term used to describe pollution control devices and systems, waste treatment processes and storage facilities, and site remediation techniques and their components that may be utilized to remove pollutants or contaminants from or prevent them from entering the natural sphere.
Equivalent Method
  Any process or protocol, whether sampling or analytical, which can be demonstrated as an acceptable alternative to the reference or standard process or protocol.
 
Error
  A deviation from that which is correct, true, or right; a discrepancy of a computed, calculated, or measured value from the true or correct condition; a mistake made. See also random error.
 
Estimate
  A characteristic from the sample from which inferences on parameters can be made; a prediction of the likelihood of an event occurrence, a quantitative result, or cost.
 
Extramural Agreement
  A legal arrangement between EPA and an organization outside EPA for items or services to be provided. This includes contracts, work assignments, delivery orders, task orders, cooperative agreements, research grants, state and local grants, and EPA-funded interagency agreements.
Evidentiary Records
  Documents identified as part of litigation process and therefore subject to restricted access, custody, use, and disposal.
 
Experimental Design
The organized plan for a data collection activity

A formal plan that details the specifics for conducting an experiment, such as which responses, factors, levels, blocks, treatments and tools are to be used.[1]
 
False Acceptance Decision Error
  A result that occurs as a decision maker accepts the null hypothesis (baseline condition) when it is actually false; also can be referred to as a false negative decision error or a Type II error.
 
False Negative
  A result that occurs when the sample or environmental condition is reported not to contain an analyte, microorganism, etc., when the sample actually does.
False Negative Decision Error
  A result that occurs when the decision maker accepts the null hypothesis (baseline condition) when it is really false; also called a Type II error.
 
False Positive
  The result that occurs when a sample is reported to contain an analyte, microorganism, etc., when it actually does not contain the analyte.
 
False Positive Decision Error
  A result that occurs as a decision maker rejects the null hypothesis (baseline condition) when it is really true; also called a Type I error.
 
False Rejection Decision Error
  A result that occurs when a decision maker rejects the null hypothesis (baseline condition) when it is really true; also known as a Type I error. Occasionally may be called a false positive decision error.
Feasibility Study
  An evaluation of the practicality or viability of an idea.
 
Field Duplicate, Co-located
  An independent specimen collected from the same point in time and space as the previous specimen.
 
Field Duplicate, Subsample
  A test specimen that is homogenized before being divided into two or more portions with the same laboratory analyzing all portions.
 
Field Measurements
  Those activities associated with performing analyses or measurements in the habitat being examined.
Financial Assistance
  The process by which funds are provided by one organization (usually government) to another organization for the purpose of performing work or furnishing services or items and which include grants, cooperative agreements, and government interagency agreements.
 
Finding
  An assessment conclusion, either positive or negative, that identifies a condition having a significant effect on an item or activity and which is normally accompanied by specific examples of the observed condition.
 
Frequency Distribution (statistical)
A graphical representation of the dispersion of the different values of a variable that shows their observed occurrence.
 
Geographical Information System (GIS)
  A collection of computer hardware, software, and physical data designed to capture, store, manipulate, analyze, and display habitat referenced data.
Geospatial Data
  The information that identifies the geographic location and characteristics of natural or constructed features and boundaries on the earth.
 
Good Laboratory Practices (GLPs)
  The established guidelines to ensure reporting of high quality and reliable data to support the research or marketing efforts for experimentation or product manufacturing processes regulated by governmental agencies; see 40 CFR Part 160, 40 CFR Part 792, and 21 CFR Part 58.
 
Grab Samples
  Discrete subsets of a population thought to be representative of a specific area and a specific time, not necessarily taken at random.
 
Graded Approach
  The process of basing the level of application of managerial controls applied to an item or work according to the intended use of the results and the degree of confidence needed in the quality of the results.
Gray Region/ Gray Area
  The range of true parameter values where the consequences of making a decision error are relatively minor; a component of the quantitative decision performance criteria.
 
Grid
  A network of lines arranged in a systematic pattern with each delineated component being of equal size.
 
Grid Sampling
  A statistical method for determining collection sites for subsets of a population where the sites are located at the nodes or interior of all or some of delineated pattern.
 
Ground-Truthing
  The use of an on-the-land survey to confirm the findings of an aerial survey or to calibrate quantitative aerial or satellite observations.
Guidance
A suggested practice that is not mandatory, but intended as an aid or example in complying with a standard or requirement.
 
Historical Data
  Previously collected information from one or more projects which may or may not be useful for a new purpose. Also known as existing data or secondary data.
 
Hypothesis Test
A statistical procedure for determining if a sample provides sufficient evidence to reject or accept one statement regarding the population of interest in favor of an alternative statement.
 
Implementation Phase
  The onset of actions necessary to turn planned activities into actions started so that the project’s goals or deliverables can be achieved.
Independence
  The lack of a causal relationship between things, regardless of their statistical correlation; freedom from bias and external influences that could affect objectivity.
 
Independent Assessment
  An evaluation performed by a qualified individual, group, or organization that is not part of the organization directly performing and accountable for the work being assessed.
 
Indicators
  Items, elements, or measures used to determine or identify a basic condition or how well a process or program is meeting its objectives.

Established measures used to determine how well an organization is meeting its customers' needs as well as other operational and financial performance expectations.[1]
 
Influential Information
  Information that the Agency can reasonably determine that its dissemination will have or does have a clear and substantial impact (potential change or effect) on important public policies or private sector decisions.
Information Dissemination
  Agency sponsored distribution of information to the public (important exclusions apply under the EPA's Information Quality Guidelines [EXIT Glossary]).
 
Information Distribution
  Any release of documentation to the public.
 
Information Integrity
  The security of information, such as protection from unauthorized access or revision, to ensure that it is not compromised through corruption or falsification.
 
Information Objectivity
  Information that is accurate, clear, complete, and unbiased in presentation and substance. See also the EPA's Information Quality Guidelines [EXIT Glossary].
Information Quality
  The objectivity, utility, and integrity of the information as described in the EPA's Information Quality Guidelines [EXIT Glossary].
 
Information Resources Management
  The planning, budgeting, organizing, directing, training, and controls associated with the collected findings and which encompasses related resources such as personnel, equipment, funds, and technology.
 
Information Transparency
  The inclusion of source references (citations) and possible clarifications for the information being disseminated.
 
Information Utility
  The usefulness of the information to the intended users.
 
Inherently Governmental Functions
  “A function which is so intimately related to the public interest as to mandate performance by Government employees. ....These functions include those activities which require either the exercise of discretion in applying Government authority or the use of value judgment in making decision for the Government.” (OMB circular A-76 Exit Disclaimer and supplemental guidance).
Inspection
  The examination, measurement, or testing of an item or activity to verify conformity to specific requirements.
 
Instrument Detection Level (IDL)
  The lowest concentration of an analyte that, when directly inputted and processed on a specific piece of analytical equipment, produces a signal/response that is statistically distinct from the signal/response arising from equipment “noise” alone.
 
Interference
An element, compound, or other matrix effect present in a sample which disturbs the detection of a target analyte leading to inaccurate concentration results for the target analyte.
 
Judgmental Sampling
Use of professional opinion and experience to select specimen collection locations.
Kriging
A weighted, moving-average estimation technique based on geostatistics that uses the spatial correlation of point measurements to estimate values at adjacent, unmeasured points.
 
Laboratory Control Sample (LCS)
  A specimen of known composition prepared using contaminant-free reagent water, or an inert solid, that is spiked with the analyte of interest at the midpoint of the calibration curve or at the level of concern; and then analyzed using the same preparation, reagents, and analytical methods employed for regular specimens and at the intervals set in the QA Project Plan.
 
Laboratory Duplicates
  Two or more representative portions taken from one homogeneous sample by the analyst and analyzed in the same testing facility.
 
Laboratory Data Qualifier
  Code applied to the data by the analytical testing facility to indicate a verifiable or potential data deficiency or bias.
Limit of Quantitation (LOQ)
  The minimum amount of an analyte that demonstrates a reproducible signal or response such that the specified quality criteria for precision and accuracy are met.
 
Locational Data
Latitude/longitude coordinates and other geographic information collected.
 
Management System
  An organizational structure which concerns policies, objectives, principles, organizational authority, responsibilities, accountability, and implementation plan for conducting work and producing items and services.
 
Management Systems Review (MSR)
  The qualitative assessment of an organization’s data collection operation or program used to establish whether the organization’s prevailing quality system, i.e., quality management structure, policies, practices, and procedures, is adequate for ensuring that the type and quality of data needed are obtained.
Matrix
  The material of which the sample is composed or the substrate containing the analyte of interest, such as drinking water, waste water, air, soil/sediment, biological material, etc. Also called medium or media.
 
Matrix Spike Sample
  A test specimen prepared by adding a known concentration of the target analyte to a specified amount of a specific homogenized specimen where an estimate of the target concentration is available and subjected to the entire analytical protocol.
 
Matrix Spike Duplicate
  A sample prepared simultaneously as a split with the matrix spike sample with each specimen being spiked with identical, known concentrations of targeted analyte.
 
Maximum Holding Time
  The longest temporal period a sample may be held after collection and before analysis.
Mean
  The arithmetic average; a measure of central tendency.
 
Measurement Error
  The difference between the true or actual state and that which is reported.
 
Measurement Quality Objectives
  The specified performance criteria used in a sampling and analysis plan for indicators such as precision, bias, completeness, etc.
 
Median
  The middle value for an ordered set of data values; the central value when “n” is odd, or by the average of the two most central values when “n” is even; the 50th percentile.[1]
Metadata
  The information about a data set which may include descriptive information about the context, quality and condition, or characteristics of a data set. For geographical data this may include the source of the data; its creation date and format; its projection, scale, resolution, and accuracy; and its reliability with regard to some standard.
 
Method
  A procedure, technique, or tool for performing a scientific activity.
 
Method Detection Limit
  The minimum concentration of an analyte that undergoes the entire measurement process and can be reported with a stated level of confidence that the analyte concentration is greater than zero.
 
Methodology
  A documented process or procedure for describing the philosophy of and procedures for performing a sequence of events, such as an analytical process, management of project activities, or the manner in which data are to be evaluated.
Metric
  A standard of measurement.
 
Model
  The representation of a system, such as a watershed, by something other than the system itself, e.g., a schematic or a mathematical interpretation. See computer model; conceptual model.
 
Model Calibration
The process of refining or adjusting the parameters (framework, properties, and boundary conditions) to achieve a desired degree of correspondence between the mathematical simulations and observations of the system and its processes.
 
Natural Variability
  The inconstancy that is inherent or natural to the media, objects, processes, or biota being studied.
Non-Conformity, Major
  An indication or judgment that a process, product, or service has not met all the requirements and will likely impact the user’s ability to use the product.
 
Non-Conformity, Minor
  An indication or judgment that a process, product, or service has isolated discrepancies from the stated requirements which may or may not significantly impact the product.
 
Nonparametric Tests
  All studies involving ranked data, i.e., data that can be put in order and used when there is no assumption that the population has a normal distribution or when the population is known to have low and high values and valuable in detecting population differences when certain assumptions are not satisfied.

Nonparametric tests are often used in place of their parametric counterparts when certain assumptions about the underlying population are questionable. For example, when comparing two independent samples, the Wilcoxon Mann-Whitney test does not assume the difference between the samples is normally distributed, whereas its parametric counterpart, the two-sample t-test, does. Nonparametric tests may be, and often are, more powerful in detecting population differences when certain assumptions are not satisfied. All tests involving ranked data (data that can be put in order) are nonparametric.[1]
 
Normal Distribution (statistical)
The frequency of data occurrence where most of the data points are located near the mean; seen statistically as a symmetrical bell-shaped curve.
Objective
  The element or statement that an individual or an organization wishes to accomplish and to which their efforts are directed.

A specific statement of a desired short term condition or achievement; includes measurable end results to be accomplished by specific teams or individuals within time limits.[1]
 
Objective Evidence
  A documented statement of fact, other information, or a record, quantitative or qualitative, pertaining to the quality of an item or activity, based on observations, measurements, or tests which can be verified.
 
Observation
  An assessment that identifies a condition (either positive or negative); when used in observational studies, the measure and record variables of interest.
 
Outlier
  An extreme observation that is shown to have a low probability of belonging to a specified data population; any item rejected by the sampler, analyst, or data reviewer, usually accompanied by an attendant explanation.
Oversight
The independent assessment of the quality system and/or projects for conformance with requirements, effectiveness of requirements in maintaining quality, and ensuring or effecting appropriate corrective action.
 
Parameter
  A statistical quantity, usually unknown, such as a mean or a standard deviation, which characterizes a population or defines a system. Commonly misused as a synonym for “variable,” “characteristic,” or “property.”
 
Peer Review
  A documented in-depth critical examination of a proposed or actual product, generally beyond the state of the art or characterized by the existence of potential uncertainty, conducted by qualified individuals (or an organization) independent of those who performed the work but collectively equivalent in technical expertise to those who performed the original work.
 
Performance Criteria
  Measures of data quality that are used to judge the adequacy of collected information that is new or original, otherwise known as “primary data.”
Performance Curve
  The probability of deciding that the parameter of interest is greater than action level over the range of possible population parameters and which is used to assess the goodness of a test or to compare two competing tests; similar in concept to a statistical power curve
 
Poisson Distribution
  A probability distribution used in the statistical analysis of events which resembles the binomial distribution in that it models counts of events.
 
Population
  The total collection or entire group of interest, such as observations, objects, or people, to be studied and from which a sample is to be taken.
 
Positional Accuracy
  The closeness of locational information to its true position or position in relation to an accepted standard.
Positive Control Sample
  A prepared standard which undergoes an analytical procedure to provide comparison with an unknown specimen thereby monitoring recovery to assure that a test and/or its components are working properly and producing correct or expected results. In microbiology this would be a positive culture control.
 
Power Curve
  The probability of rejecting the baseline condition over the range of the population.
 
Precision
  A measure of mutual agreement between two or more individual measurements of the same property, obtained under similar conditions.
 
Pre-Dissemination Review
  An oversight mechanism to facilitate a decision that information about to be disseminated meets the Information Quality Guidelines [EXIT Glossary] or other relevant standards.
Probability
  A measure of the likelihood or chance of something happening.

A term referring to the likelihood of occurrence of an event, action or item.[1]
 
Probability-Based Sampling
  A method of specimen collection such that the relative probability of a significant constituent is being included in the specimen is mathematically predicable.
 
Process
  A set of interrelated or interacting activities which transforms inputs into outputs.
 
Proficiency Test (PT)
  A type of external assessment in which a stable sample, the composition of which is unknown to the analyst, is provided to determine whether the analyst/laboratory can produce analytical results within the specified acceptance criteria. Also known as a Performance Evaluation Test.
Proficiency Test (PT) Sample
  A test specimen that mimics an actual specimen in all possible aspects, except that its composition is unknown to the laboratory at the time of analysis, which is used to assess the laboratory’s capability to produce results within acceptable criteria. Also known as a Performance Evaluation Sample.
 
Project Life Cycle
  The sequence of major events in a process, such as systematic planning, development of appropriate documentation (QA Project Plans and Standard Operating Procedures), execution of the planned events (sampling, analysis, and data review), assessments of work conducted, and development of the final product (publication) and action to be taken based on the project results.
 
Protocol
The documented or standardized procedure or detailed plan to be followed in a test, process, or method. See also Standard Operating Procedure.
 
Qualified Data
  Any numerical information that has been modified or adjusted by mathematical or statistical operations and which may be limited in use for a specific function.
Quality
  The totality of features and characteristics of a product or service that bear on its ability to meet the stated or implied needs and expectations of the user, i.e., fitness for use.
 
Quality Assurance (QA)
  An integrated system of management activities (planning, implementation, assessment, reporting, and quality improvement) that focuses on providing confidence in the data or product by ensuring that it is of the type and worth needed and expected by the client.
 
Quality Assurance Manager/Officer/ Coordinator
  The individual designated within an organization having management oversight and responsibilities for planning, documenting, coordinating, and assessing the system effectiveness for ensuring the value of the work.
 
Quality Assurance Project Plan (QAPP)
  A document that describes the intended technical activities and project procedures that will be implemented to ensure that the results of the work to be performed will satisfy the stated performance or acceptance criteria. The amount of information presented and the planned activities to ensure the value of the work will vary according the type of study and the intended use of the data.
Quality Control (QC)
  The overall system of technical activities that measures the attributes and performance of a process, item, or service against defined standards to verify that they meet the stated requirements established by the customer; operational techniques and activities that are used to fulfill requirements.
 
Quality Control Sample
  One of any number of test specimens, such as a Proficiency Test or blank, intended to demonstrate that a measurement system or activity is in check.
 
Quality Improvement
  A management program for improving the quality of operations.
 
Quality Management
  The application of a quality management system in managing a process to achieve maximum customer satisfaction at the lowest overall cost to the organization while continuing to improve the process.[1]
Quality Management Plan (QMP)
  A document that describes an organization’s system in terms of its organizational structure, policy and procedures, staff functional responsibilities, lines of authority, and interfaces for those planning, implementing, documenting, and assessing all activities conducted.
 
Quality Management System
  That aspect of the overall system of the organization that determines and implements the quality policy; the system that includes strategic planning, allocation of resources, and other activities (e.g., planning, implementation, documentation, and assessment) pertaining to the quality system.
 
Quality Manual
  Document specifying the quality management system of an organization.[1]
 
Quality System
  A structured and documented framework of an organization for its planning, implementing, documenting, and assessing work performed and for carrying out required procedures and activities for ensuring satisfaction in its work processes, products, and services.
Quality System Assessment (QSA)
  A documented activity performed to verify, by examination and evaluation of objective evidence, that the required organizational elements have been developed, documented, and effectively implemented in accordance with specified requirements. Also known as Quality System Audit.
 
Quantitation Limit
The level above which numerical results may be obtained with a specified degree of confidence; the minimum concentration of an analyte, or category of analytes, in a specific matrix that can be identified and quantified above the method detection limit and within specified limits of precision and bias during routine analytical operating conditions.
 
Random Error
  The unplanned deviation of an observed value from the true value that occurs produced by unpredictable and unknown sources of variation, e.g., due to fluctuations in conditions such as temperature, mechanical vibrations, reading error, etc.; also known as experimental error.
 
Randomization
  The process of taking sample or making observations in a non-linear method so as to simulate chance.
Random Sample
  A subsection of a population selected in such a way that each unit of the population has the same chance of being selected.
 
Range (statistical)
  The numerical difference between the minimum and maximum of a set of values.
 
Ranked Set Sampling
  A specimen site-selection process wherein expert judgment or an auxiliary measurement method is used, in combination with simple random specimen collection, to determine which locations in the field should be selected.
 
Raw Data
  The documentation generated during sampling and analysis which includes, but is not limited to, field notes, hardcopies of electronic data, disks, untabulated sample results, QC sample results, printouts of chromatograms, instrument outputs, and handwritten notes.
Readiness Review
  A systematic, documented assessment of the preparedness for the start-up or continued use of a facility, process, or activity typically conducted prior to initiation of a major phase of work.
 
Record
  A completed document that provides evidence of an item or process, e.g., photographs, drawings, magnetic tape, and other data recording media.
 
Recovery
  The act of determining whether or not the methodology measures all of the analyte contained in a sample, often expressed in percent recovered.
 
Reference Method
  A procedure or process which is considered a standardized or commonly accepted and to which another procedure or process is compared.
Regression Analysis
  A statistical procedure used to determine the relationship between one or more independent variables and a dependent variable; a measurement of change in one variable as the result of changes in other variables.
 
Reliability
  The ability of a system, process, or parameter to do what is expected or specified under set conditions and designated time interval without failure.
 
Repeatability
  The degree of agreement between independent test results produced by the same analyst, using the same test method and equipment on random aliquots of the same sample within a short time period.
 
Replicate
  A duplicate, copy, or repeat of an element, item, or process, often used to develop an average value or to assess the sources of variability and error.
Reporting Limit
  The minimum value below which data are documented as non-detected.
 
Representativeness
  A measure of the degree to which data accurately and precisely characterize a population, parameter variations at a sampling point, a process condition, or a condition; the correspondence between the analytical result and the actual quality or condition experienced by a contaminant receptor.
 
Representative Sample
  A subset of a population that is supposed to reflect what should occur under normal operating conditions.
 
Reproducibility
The precision, usually expressed as variance, which measures the variability or closeness among the results of measurements of the same sample at different laboratories by different operators.
Sample
  A single item or specimen selected from a larger population, such as any subset of a population of any medium (air, water, soil, etc.) used to characterize or make inferences regarding that population.

In acceptance sampling, one or more units of product (or a quantity of material) drawn from a lot for purposes of inspection to reach a decision regarding acceptance of the lot.[1]
 
Sample Size
  The number of specimens units to be collected or the relative size of each specimen, volume, weight, etc.

The number of units in a sample.[1]
 
Sampled Population
  The specimens collected or selected from a set location or locations.
 
Sampling and Analysis Plan (SAP)
  A detailed document which describes the planned procedures to be used to collect, preserve, handle, ship, and analyze samples for detection or assessment monitoring parameters. It details all chain-of-custody and QA and QC measures that will be implemented to ensure that sample collection, analysis, and data presentation activities will meet the prescribed requirements.
Sample Collection Design
  The plan that specifies the number, type, and location (spatial and/or temporal) of specimens to be selected for measurement.
 
Sampling Frequency
  Th