ASTM D2777-03
(Practice)Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
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 or . 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. Precision-and-bias statements authorized by this paragraph shall include the date of approval by Committee D19.
1.6 In principle, all test methods are covered by this practice.
1.7 In Section 12 this practice shows exemplary precision-and-bias-statement formats for: (1) test methods yielding a numerical 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.
1.8 All studies, even those exempt from some requirements under or , shall receive approval from the Results Advisor before being conducted (see Section 8) and after completion (see Section 13).
1.9 This practice satisfies the QC requirements of Practice D 5847.
1.10 It is the intent of this practice that task groups make every effort to retain all the data from their round-robin studies. Values should not be eliminated unless solid evidence exists for their exclusion. The Results Advisor should work closely with the task groups to effect this goal.
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Designation:D2777–03
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 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 (e) indicates an editorial change since the last revision or reapproval.
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
shallbeconductedtoprovidethebestpossiblelimitedbasisfor
2
cannot be achieved will meet both ASTM requirements (1)
estimating the overall and single-operator standard deviations.
and the related requirements of this practice. Precision-and-
1.3.1 Examples of acceptable scaled-down studies are the
bias statements authorized by this paragraph shall include the
local-area studies conducted by Subcommittee D19.24 on
date of approval by Committee D19.
microbiological methods because of inherent sample instabil-
1.6 In principle, all test methods are covered by this
ity. These studies involve six or more completely independent
practice.
local-area analysts who can begin analysis of uniform samples
1.7 In Section 12 this practice shows exemplary precision-
at an agreed upon time.
and-bias-statement formats for: (1) test methods yielding a
1.3.2 If uniform samples are not feasible under any circum-
numerical measure, (2) test methods yielding a non-numerical
stances, a statement of single-operator precision will meet the
report of success or failure based on criteria specified in the
requirements of this practice. Whenever possible, this state-
procedure, and (3) test methods specifying that procedures in
ment should be developed from data generated by independent
another ASTM test method are to be used with only insignifi-
multiple operators, each doing replicate analyses on indepen-
cant modifications.
dent samples (of a specific matrix type), which generally fall
1.8 All studies, even those exempt from some requirements
within specified concentration ranges (see 7.2.5.2( 3)).
under 1.3 or 1.5, shall receive approval from the Results
1.3.3 This practice is not applicable to methodology involv-
Advisor before being conducted (see Section 8) and after
ing continuous sampling or continuous measurement, or both,
completion (see Section 13).
of specific constituents and properties.
1.9 ThispracticesatisfiestheQCrequirementsofPracticeD
1.3.4 This practice is also not applicable to open-channel
5847.
flow measurements.
1.10 It is the intent of this practice that task groups make
everyefforttoretainallthedatafromtheirround-robinstudies.
1
Valuesshouldnotbeeliminatedunlesssolidevidenceexistsfor
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, and Statistical Methods.
2
Current edition approved Aug. 10, 2003. Published September 2003. Originally The boldface numbers in parentheses refer to the list of standards at the end of
approved in 1969. Last previous edition approved in 1998 as D 2777 – 98. this practice.
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