Quality Assurance Glossary

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Accuracy - The extent to which the measured value of a quantity agrees with the accepted value for that quantity.

Assignable cause - A cause believed to be responsible for an identifiable change of precision or accuracy of a measurement process.

Bias - Systematic error that is manifested as a consistent positive or negative deviation from the known or true value. It differs from random error which shows no such deviation.

Blank Solution - Solution that is free of the analyte(s) of interest. Such a solution would be used to develop specific types of blank samples as described below.

Environmental data - any measurements or information that describe environmental processes, location, or conditions; ecological or health effects and consequences; or the performance of environmental technology. For EPA, environmental data include information collected directly from measurements, produced from models, and compiled from other sources such as data bases or the literature.

Field Blank - a blank solution that is subjected to all aspects of sample collection, field processing, preservation, transportation, and laboratory handling as an environmental sample.

Filter Blank - a blank solution that is filtered in the same manner and through the same filter apparatus used for an environmental sample.

Preservation Blank - a blank solution that is treated with the same preservatives used for an environmental sample.

Refrigerator Blank - a blank solution that is put in the same type of bottle used for an environmental sample and stored adjacent to an environmental sample in a refrigerated storage area.

Sampler Blank - a blank solution that is poured or pumped through the same field sampler used for the collection of an environmental sample.

Trip Blank - a blank solution that is put in the same type of bottle used for an environmental sample and kept with the set of sample bottles both before and after sample collection.

Blind Sample - A sample submitted for analysis whose composition is known to the submitter but unknown to the analyst.

Certified Reference Material (CRM) - A reference material, for which one or more property values are certified by a technically valid procedure, accompanied by or traceable to a certificate or other documentation which is issued by a certifying body.

Concurrent Samples - A type of replicate sample in which the samples are collected by two or more people collecting samples simultaneously or by one person alternating subsamples between two or more collection bottles.

Double Blind Sample - A sample whose composition is known by the submitter but submitted to an analyst in such a way that neither its composition nor its identification as a check sample are known to the latter.

Duplicate Analysis - The analysis or measurement of the variable of interest performed as identically as possible on two subsamples of a sample.

Duplicate Sample - The special case of replicate samples that consists of two samples.

Measured Value - The stated or recorded value after all appropriate adjustments and corrections, if any, have been incorporated into the observed value.

Nonconformity - A departure of a quality characteristic from its intended level or state that occurs with severity sufficient to cause an associated product or service not to meet a specification requirement.

Observed Value - A raw, uncorrected value; the magnitude of a specified measurement, a variable, or a unit of space, time or quantity; a datum.

Outlier - A datum which appears to deviate markedly from that for other members of the sample in which it occurs.

Performance Evaluation - An audit in which the quantitative data generated in a measurement system are obtained independently and compared with routinely obtained data in order to evaluate the proficiency of an individual or group.

Precision - The degree of similarity among independent measurements of the same quantity, without reference to the known or true value. It often is presented as the inverse of the standard deviation.

Quality - The totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs.

Quality Assurance (QA) - All those planned or systematic actions necessary to provide adequate confidence that a product or service is of the type and quality needed and expected by the customer.

Quality Assurance Program - The documented plans for implementing the quality system.

Quality Assurance Project Plan (QAPP) - a document describing in comprehensive detail the necessary quality assurance, quality control, and other technical activities that must be implemented to ensure that the results of the work performed will satisfy the stated performance criteria.

Quality Management Plan (QMP) - a formal document describing the management policies, objectives, principles, organizational authority, responsibilities, accountability, and implementation
plan of an organization or group for ensuring quality in its products.

Quality Audit - A systematic and independent examination and evaluation to determine whether quality activities and results comply with planned arrangements and whether these arrangements are implemented effectively and are suitable to achieve objectives.

Quality Circle - A small group of individuals with related interests that meet at regular intervals to consider problems or other matters related to the quality of outputs of a process and to the correction of problems or to the improvement of quality.

Quality Control (QC) - The operational techniques and the activities used to fulfill and verify requirements of quality.

Quality Management - That aspect of the overall management function that determines and implements the quality policy.

Quality Policy - The overall intentions and direction of an organization as regards quality as formally expressed by top management.

Quality System - The organizational structure, responsibilities, procedures, processes, and resources for implementing quality management.

Reference Material - A material or substance one or more properties of which are sufficiently well established to be used for the assessment of a measurement method or for assigning values to materials.

Replicate Samples - A group of samples, collected in a manner such that the samples are thought to be essentially identical in composition. Replicate is the general case for which duplicate is the special case consisting of two samples.

Sample - A representative part of a larger whole; a finite part or subset of a statistical population.

Sequential Samples - A type of replicate sample in which the samples are collected one after the other, typically over a short period of time.

Spike Sample - A sample to which known concentrations of specific analytes have been added in such a manner as to minimize the change in the matrix of the original sample.

Split Sample - A type of replicate sample in which a sample is split into subsamples contemporaneous in time and space.

Standard - Something established for use as a rule or basis of comparison in measuring or judging capacity, quantity, content, extent, value, or quality.

Standard Method - An assemblage of techniques and procedures based on consensus, or other criteria, and often evaluated for its reliability by a collaborative testing and having received organizational approval.

Standard Operating Procedure (SOP) - A written document which details the method of an operation, analysis, or action whose techniques and procedures are thoroughly prescribed and which is accepted as the method for performing certain routine or repetitive tasks. It may be a standard method or one developed by the user.

Standard Reference Material (SRM) - A certified reference material (CRM) produced by the U.S. National Institute of Science and Technology.

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