ASTM D2777-08e1
(Practice)Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
SIGNIFICANCE AND USE
Following this practice should result in precision-and-bias statements that can be achieved by any laboratory properly using the test method studied. These precision-and-bias statements provide the basis for generic limits for use in the Quality Control section of the test method. Optionally, the detection and quantitation values provide estimates of the level at which most laboratories should be able to achieve confident detection and meet the minimum precision (expressed as relative standard deviation) expected.
The method specifies the matrices for which the test method is appropriate. The collaborative test corroborates the write-up within the limitations of the test design. An extensive test can only use representative matrices so that universal applicability cannot be implied from the results.
The fundamental assumption of the collaborative study is that the matrices tested, the concentrations tested, and the participating laboratories are a representative and fair evaluation of the scope and applicability of the test method as written.
SCOPE
1.1 This practice establishes uniform standards for estimating and expressing the precision and bias of applicable test methods for Committee D19 on Water.
1.2 Except as specified in 1.3, 1.4, and 1.5, this practice requires the task group proposing a new test method to carry out a collaborative study from which statements for precision (overall and single-operator standard-deviation estimates) and bias can be developed. This practice provides general guidance to task groups in planning and conducting such determinations of precision and bias.
1.3 If a full-scale collaborative study is not technically feasible, due to the nature of the test method or instability of samples, the largest feasible scaled-down collaborative study shall be conducted to provide the best possible limited basis for estimating the overall and single-operator standard deviations.
1.3.1 Examples of acceptable scaled-down studies are the local-area studies conducted by Subcommittee D19.24 on microbiological methods because of inherent sample instability. These studies involve six or more completely independent local-area analysts who can begin analysis of uniform samples at an agreed upon time.
1.3.2 If uniform samples are not feasible under any circumstances, a statement of single-operator precision will meet the requirements of this practice. Whenever possible, this statement should be developed from data generated by independent multiple operators, each doing replicate analyses on independent samples (of a specific matrix type), which generally fall within specified concentration ranges (see 7.2.5.2 (3)).
1.3.3 This practice is not applicable to methodology involving continuous sampling or continuous measurement, or both, of specific constituents and properties.
1.3.4 This practice is also not applicable to open-channel flow measurements.
1.4 A collaborative study that satisfied the requirements of the version of this practice in force when the study was conducted will continue to be considered an adequate basis for the precision-and-bias statement required in each test method. If the study does not satisfy the current minimum requirements for a collaborative study, a statement listing the study's deficiencies and a reference to this paragraph shall be included in the precision-and-bias statement as the basis for an exemption from the current requirements.
1.5 This paragraph relates to special exemptions not clearly acceptable under 1.3 or 1.4. With the approval of Committee D19 on the recommendation of the Results Advisor and the Technical Operations Section of the Executive Subcommittee of Committee D19, a statement giving a compelling reason why compliance with all or specific points of this practice cannot be achieved will meet both ASTM requirements (1) and the related requirements of this practice. In addition, Committee D19, through a Main Commi...
General Information
Relations
Buy Standard
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
´1
Designation: D2777 − 08
StandardPractice for
Determination of Precision and Bias of Applicable Test
1
Methods of Committee D19 on Water
This standard is issued under the fixed designation D2777; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
´ NOTE—Editorially added reference to Adjunct DQCALC in Referenced Documents in November 2008.
1. Scope 1.4 A collaborative study that satisfied the requirements of
the version of this practice in force when the study was
1.1 This practice establishes uniform standards for estimat-
conducted will continue to be considered an adequate basis for
ing and expressing the precision and bias of applicable test
the precision-and-bias statement required in each test method.
methods for Committee D19 on Water.
If the study does not satisfy the current minimum requirements
1.2 Except as specified in 1.3, 1.4, and 1.5, this practice
for a collaborative study, a statement listing the study’s
requires the task group proposing a new test method to carry
deficiencies and a reference to this paragraph shall be included
out a collaborative study from which statements for precision
in the precision-and-bias statement as the basis for an exemp-
(overall and single-operator standard-deviation estimates) and
tion from the current requirements.
bias can be developed.This practice provides general guidance
1.5 This paragraph relates to special exemptions not clearly
to task groups in planning and conducting such determinations
acceptable under 1.3 or 1.4. With the approval of Committee
of precision and bias.
D19 on the recommendation of the Results Advisor and the
1.3 If a full-scale collaborative study is not technically
Technical Operations Section of the Executive Subcommittee
feasible, due to the nature of the test method or instability of
of Committee D19, a statement giving a compelling reason
samples, the largest feasible scaled-down collaborative study
why compliance with all or specific points of this practice
2
shallbeconductedtoprovidethebestpossiblelimitedbasisfor
cannot be achieved will meet both ASTM requirements (1)
estimating the overall and single-operator standard deviations.
and the related requirements of this practice. In addition,
1.3.1 Examples of acceptable scaled-down studies are the
Committee D19, through a Main Committee ballot, may
local-area studies conducted by Subcommittee D19.24 on
approve publication of a “Preliminary” Standard Method for a
microbiological methods because of inherent sample instabil-
period not to exceed 5 years. Preliminary Standards must
ity. These studies involve six or more completely independent
contain a minimum of a single-operator precision-and-bias
local-area analysts who can begin analysis of uniform samples
statement and a Quality Control section based on the single
at an agreed upon time.
operator data. Publication of a Preliminary Standard is condi-
1.3.2 If uniform samples are not feasible under any
tional on the approval of a full D2777 collaborative study
circumstances, a statement of single-operator precision will
design for the standard. Precision-and-bias statements autho-
meet the requirements of this practice.Whenever possible, this
rized by this paragraph shall include the date of approval by
statement should be developed from data generated by inde-
Committee D19.
pendent multiple operators, each doing replicate analyses on
1.6 In principle, all test methods are covered by this
independent samples (of a specific matrix type), which gener-
practice.
ally fall within specified concentration ranges (see 7.2.5.2 (3)).
1.3.3 This practice is not applicable to methodology involv- 1.7 In Section 12 this practice shows exemplary precision-
ing continuous sampling or continuous measurement, or both, and-bias-statement formats for: (1) test methods yielding a
of specific constituents and properties. numerical measure, (2) test methods yielding a non-numerical
1.3.4 This practice is also not applicable to open-channel report of success or failure based on criteria specified in the
flow measurements. procedure, and (3) test methods specifying that procedures in
another ASTM test method are to be used with only insignifi-
1 cant modifications.
This practice is under the jurisdiction ofASTM Committee D19 on Water and
is the direct responsibility of Subcommittee D19.02 on Quality Systems,
Specification, and Statistics.
Current edition approved Nov. 12, 2008. Published February 2008. Originally
2
approved in 1969. Last previous edition approved in 2006 as D2777 – 06. DOI: The boldface numbers in parentheses refer to the list of standa
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation:D2777–06 Designation:D2777–08
Standard Practice for
Determination of Precision and Bias ofApplicable Test
1
Methods of Committee D19 on Water
This standard is issued under the fixed designation D 2777; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
´ NOTE—Editorially added reference to Adjunct DQCALC in Referenced Documents in November 2008.
1. Scope
1.1 This practice establishes uniform standards for estimating and expressing the precision and bias of applicable test methods
for Committee D19 on Water.
1.2 Except as specified in 1.3, 1.4, and 1.5, this practice requires the task group proposing a new test method to carry out a
collaborative study from which statements for precision (overall and single-operator standard-deviation estimates) and bias can be
developed.Thispracticeprovidesgeneralguidancetotaskgroupsinplanningandconductingsuchdeterminationsofprecisionand
bias.
1.3 If a full-scale collaborative study is not technically feasible, due to the nature of the test method or instability of samples,
the largest feasible scaled-down collaborative study shall be conducted to provide the best possible limited basis for estimating the
overall and single-operator standard deviations.
1.3.1 Examples of acceptable scaled-down studies are the local-area studies conducted by Subcommittee D19.24 on
microbiological methods because of inherent sample instability. These studies involve six or more completely independent
local-area analysts who can begin analysis of uniform samples at an agreed upon time.
1.3.2 If uniform samples are not feasible under any circumstances, a statement of single-operator precision will meet the
requirements of this practice.Whenever possible, this statement should be developed from data generated by independent multiple
operators, each doing replicate analyses on independent samples (of a specific matrix type), which generally fall within specified
concentration ranges (see 7.2.5.2 ( 3)).
1.3.3 This practice is not applicable to methodology involving continuous sampling or continuous measurement, or both, of
specific constituents and properties.
1.3.4 This practice is also not applicable to open-channel flow measurements.
1.4 A collaborative study that satisfied the requirements of the version of this practice in force when the study was conducted
willcontinuetobeconsideredanadequatebasisfortheprecision-and-biasstatementrequiredineachtestmethod.Ifthestudydoes
not satisfy the current minimum requirements for a collaborative study, a statement listing the study’s deficiencies and a reference
to this paragraph shall be included in the precision-and-bias statement as the basis for an exemption from the current requirements.
1.5 This paragraph relates to special exemptions not clearly acceptable under 1.3 or 1.4. With the approval of Committee D19
ontherecommendationoftheResultsAdvisorandtheTechnicalOperationsSectionoftheExecutiveSubcommitteeofCommittee
D19, a statement giving a compelling reason why compliance with all or specific points of this practice cannot be achieved will
2
meet both ASTM requirements (1) and the related requirements of this practice. In addition, Committee D19, through a Main
Committee ballot, may approve publication of a “Preliminary” Standard Method for a period not to exceed 5 years. Preliminary
Standards must contain a minimum of a single-operator precision-and-bias statement and a Quality Control section based on the
single operator data. Publication of a Preliminary Standard is conditional on the approval of a full D 2777 collaborative study
designforthestandard.Precision-and-biasstatementsauthorizedbythisparagraphshallincludethedateofapprovalbyCommittee
D19.
1.6 In principle, all test methods are covered by this practice.
1.7 InSection12thispracticeshowsexemplaryprecision-and-bias-statementformatsfor:(1)testmethodsyieldinganumerical
measure, (2) test methods yielding a non-numerical report of success or failure based on criteria specified in the procedure, and
(3) test methods specifying that procedures in another ASTM test method are to be used with only insignificant modifications.
1
This practice is under the jurisdiction ofASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.02 on General Specifications, Technical
Resources, Quality Systems,
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.