ASTM D2777-13

Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water

SIGNIFICANCE AND USE
5.1 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.  
5.2 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.  
5.3 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. Statements of precision and bias in test methods are required by the Form and Style for ASTM Standards, “Section A21. Precision and Bias (Mandatory).” In principle, all test methods are covered by this practice.  
1.2 Except as specified in 1.4, 1.5, and 1.6, 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 This practice also provides guidance to task groups for conducting limited-scale collaborative studies (known as “comparability studies”) for test methods that have been revised, when such revision includes substantive modifications. Examples of substantive modifications may include, but are not limited to, changes in mandatory or allowable instrumentation, reagents, reaction times, etc.  
1.3.1 Changes to applicable water matrices in the Scope of a method may constitute a substantive modification under this provision. However, recognize that even the original collaborative study may not have used all the various matrix types specified in the method’s original Scope.  
1.3.2 A method's concentration-range extension that is deemed to merit additional collaborative testing (even without a method modification that would otherwise be considered substantive) shall require a full collaborative study, as described in Sections 7.1-7.5, but only at Youden-pair concentrations representative of the extended range. Note that such a collaborative study could involve as little as a single-sample Youden-pair study in a single reproducible matrix.  
1.3.3 Whether a revision to a test method includes substantive modification shall be determined by consensus of the Committee.  
1.4 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.  
1.4.1 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.  
1.4.2 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 stat...

General Information

• Status: Historical
• Publication Date: 31-Dec-2012
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.02 - Quality Systems, Specification, and Statistics

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
Designation: D2777 − 13
Standard Practice 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. Scope 1.3.3 Whether a revision to a test method includes substan-
tive modification shall be determined by consensus of the
1.1 This practice establishes uniform standards for estimat-
Committee.
ing and expressing the precision and bias of applicable test
methods for Committee D19 onWater. Statements of precision
1.4 If a full-scale collaborative study is not technically
and bias in test methods are required by the Form and Style for
feasible, due to the nature of the test method or instability of
ASTM Standards, “Section A21. Precision and Bias (Manda-
samples, the largest feasible scaled-down collaborative study
tory).” In principle, all test methods are covered by this
shallbeconductedtoprovidethebestpossiblelimitedbasisfor
practice.
estimating the overall and single-operator standard deviations.
1.4.1 Examples of acceptable scaled-down studies are the
1.2 Except as specified in 1.4, 1.5, and 1.6, this practice
local-area studies conducted by Subcommittee D19.24 on
requires the task group proposing a new test method to carry
microbiological methods because of inherent sample instabil-
out a collaborative study from which statements for precision
ity. These studies involve six or more completely independent
(overall and single-operator standard-deviation estimates) and
local-area analysts who can begin analysis of uniform samples
bias can be developed.This practice provides general guidance
at an agreed upon time.
to task groups in planning and conducting such determinations
of precision and bias. 1.4.2 If uniform samples are not feasible under any
circumstances, a statement of single-operator precision will
1.3 This practice also provides guidance to task groups for
meet the requirements of this practice.Whenever possible, this
conducting limited-scale collaborative studies (known as
statement should be developed from data generated by inde-
“comparability studies”) for test methods that have been
pendent multiple operators, each doing replicate analyses on
revised,whensuchrevisionincludessubstantivemodifications.
independent samples (of a specific matrix type), which gener-
Examplesofsubstantivemodificationsmayinclude,butarenot
ally fall within specified concentration ranges (see 7.2.5.2 (3)).
limited to, changes in mandatory or allowable instrumentation,
1.4.3 This practice is not applicable to methodology involv-
reagents, reaction times, etc.
ing continuous sampling or continuous measurement, or both,
1.3.1 Changes to applicable water matrices in the Scope of
of specific constituents and properties.
a method may constitute a substantive modification under this
provision. However, recognize that even the original collab- 1.4.4 This practice is also not applicable to open-channel
flow measurements.
orative study may not have used all the various matrix types
specified in the method’s original Scope.
1.5 A collaborative study that satisfied the requirements of
1.3.2 A method’s concentration-range extension that is
the version of this practice in force when the study was
deemed to merit additional collaborative testing (even without
conducted will continue to be considered an adequate basis for
a method modification that would otherwise be considered
the precision-and-bias statement required in each test method.
substantive) shall require a full collaborative study, as de-
If the study does not satisfy the current minimum requirements
scribed in Sections 7.1-7.5, but only at Youden-pair concen-
for a collaborative study, a statement listing the study’s
trations representative of the extended range. Note that such a
deficiencies and a reference to this paragraph shall be included
collaborative study could involve as little as a single-sample
in the precision-and-bias statement as the basis for an exemp-
Youden-pair study in a single reproducible matrix.
tion from the current requirements.
1.6 This paragraph relates to special exemptions not clearly
1
acceptable under 1.4 or 1.5. With the approval of Committee
This practice is under the jurisdiction ofASTM Committee D19 on Water and
is the direct responsibility of Subcommittee D19.02 on Quality Systems,
D19 on the recommendation of the Results Advisor and the
Specification, and Statistics.
Technical Operations Section of the Executive Subcommittee
Current edition approved Jan. 1, 2013. Published February 2013. Origina
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM 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.
Designation: D2777 − 12 D2777 − 13
Standard Practice 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. 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. Statements of precision and bias in test methods are required by the Form and Style for ASTM
Standards, “Section A21. Precision and Bias (Mandatory).” In principle, all test methods are covered by this practice.
1.2 Except as specified in 1.4, 1.5, and 1.6, 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 This practice also provides guidance to task groups for conducting limited-scale collaborative studies (known as
“comparability studies”) for test methods that have been revised, when such revision includes substantive modifications. Examples
of substantive modifications may include, but are not limited to, changes in mandatory or allowable instrumentation, reagents,
reaction times, etc.
1.3.1 Changes to applicable water matrices in the Scope of a method may constitute a substantive modification under this
provision. However, recognize that even the original collaborative study may not have used all the various matrix types specified
in the method’s original Scope.
1.3.2 A method’s concentration-range extension that is deemed to merit additional collaborative testing (even without a method
modification that would otherwise be considered substantive) shall require a full collaborative study, as described in Sections
7.1-7.5, but only at Youden-pair concentrations representative of the extended range. Note that such a collaborative study could
involve as little as a single-sample Youden-pair study in a single reproducible matrix.
1.3.3 Whether a revision to a test method includes substantive modification shall be determined by consensus of the Committee.
1.4 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.
1.4.1 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.
1.4.2 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)).
1.4.3 This practice is not applicable to methodology involving continuous sampling or continuous measurement, or both, of
specific constituents and properties.
1.4.4 This practice is also not applicable to open-channel flow measurements.
1.5 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
This practice is under the jurisdiction of ASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.02 on Quality Systems, Specification,
and Statistics.
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