ASTM D7366-08(2019)
(Practice)Standard Practice for Estimation of Measurement Uncertainty for Data from Regression-based Methods
Standard Practice for Estimation of Measurement Uncertainty for Data from Regression-based Methods
SIGNIFICANCE AND USE
5.1 Appropriate application of this practice should result in an estimate of the test-method’s uncertainty (at any concentration within the working range), which can be compared with data-quality objectives to see if the uncertainty is acceptable.
5.2 With data sets that compare recovered concentration with true concentration, the resulting regression plot allows the correction of the recovery data to true values. Reporting of such corrections is at the discretion of the user.
5.3 This practice should be used to estimate the measurement uncertainty for any application of a test method where measurement uncertainty is important to data use.
SCOPE
1.1 This practice establishes a standard for computing the measurement uncertainty for applicable test methods in Committee D19 on Water. The practice does not provide a single-point estimate for the entire working range, but rather relates the uncertainty to concentration. The statistical technique of regression is employed during data analysis.
1.2 Applicable test methods are those whose results come from regression-based methods and whose data are intra-laboratory (not inter-laboratory data, such as result from round-robin studies). For each analysis conducted using such a method, it is assumed that a fixed, reproducible amount of sample is introduced.
1.3 Calculation of the measurement uncertainty involves the analysis of data collected to help characterize the analytical method over an appropriate concentration range. Example sources of data include: (1) calibration studies (which may or may not be conducted in pure solvent), (2) recovery studies (which typically are conducted in matrix and include all sample-preparation steps), and (3) collections of data obtained as part of the method’s ongoing Quality Control program. Use of multiple instruments, multiple operators, or both, and field-sampling protocols may or may not be reflected in the data.
1.4 In any designed study whose data are to be used to calculate method uncertainty, the user should think carefully about what the study is trying to accomplish and much variation should be incorporated into the study. General guidance on designing studies (for example, calibration, recovery) is given in Appendix X1. Detailed guidelines on sources of variation are outside the scope of this practice, but general points to consider are included in Appendix X2, which is not intended to be exhaustive. With any study, the user must think carefully about the factors involved with conducting the analysis, and must realize that the computed measurement uncertainty will reflect the quality of the input data.
1.5 Associated with the measurement uncertainty is a user-chosen level of statistical confidence.
1.6 At any concentration in the working range, the measurement uncertainty is plus-or-minus the half-width of the prediction interval associated with the regression line.
1.7 It is assumed that the user has access to a statistical software package for performing regression. A statistician should be consulted if assistance is needed in selecting such a program.
1.8 A statistician also should be consulted if data transformations are being considered.
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D7366 − 08 (Reapproved 2019)
Standard Practice for
Estimation of Measurement Uncertainty for Data from
1
Regression-based Methods
This standard is issued under the fixed designation D7366; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope analysis, and must realize that the computed measurement
uncertainty will reflect the quality of the input data.
1.1 This practice establishes a standard for computing the
1.5 Associated with the measurement uncertainty is a user-
measurement uncertainty for applicable test methods in Com-
chosen level of statistical confidence.
mittee D19 on Water. The practice does not provide a single-
point estimate for the entire working range, but rather relates
1.6 Atanyconcentrationintheworkingrange,themeasure-
the uncertainty to concentration. The statistical technique of
ment uncertainty is plus-or-minus the half-width of the predic-
regression is employed during data analysis.
tion interval associated with the regression line.
1.2 Applicable test methods are those whose results come
1.7 It is assumed that the user has access to a statistical
from regression-based methods and whose data are intra-
software package for performing regression. A statistician
laboratory (not inter-laboratory data, such as result from
should be consulted if assistance is needed in selecting such a
round-robinstudies).Foreachanalysisconductedusingsucha
program.
method, it is assumed that a fixed, reproducible amount of
1.8 A statistician also should be consulted if data transfor-
sample is introduced.
mations are being considered.
1.3 Calculationofthemeasurementuncertaintyinvolvesthe
1.9 This standard does not purport to address all of the
analysis of data collected to help characterize the analytical
safety concerns, if any, associated with its use. It is the
method over an appropriate concentration range. Example
responsibility of the user of this standard to establish appro-
sources of data include: (1) calibration studies (which may or
priate safety, health, and environmental practices and deter-
may not be conducted in pure solvent), (2) recovery studies
mine the applicability of regulatory limitations prior to use.
(which typically are conducted in matrix and include all
1.10 This international standard was developed in accor-
sample-preparation steps), and (3) collections of data obtained
dance with internationally recognized principles on standard-
as part of the method’s ongoing Quality Control program. Use
ization established in the Decision on Principles for the
of multiple instruments, multiple operators, or both, and
Development of International Standards, Guides and Recom-
field-sampling protocols may or may not be reflected in the
mendations issued by the World Trade Organization Technical
data.
Barriers to Trade (TBT) Committee.
1.4 In any designed study whose data are to be used to
2. Referenced Documents
calculate method uncertainty, the user should think carefully
2
about what the study is trying to accomplish and much
2.1 ASTM Standards:
variation should be incorporated into the study. General guid-
D1129Terminology Relating to Water
ance on designing studies (for example, calibration, recovery)
3. Terminology
is given in Appendix X1. Detailed guidelines on sources of
variation are outside the scope of this practice, but general
3.1 Definitions:
points to consider are included in Appendix X2, which is not
3.1.1 For definitions of terms used in this standard, refer to
intended to be exhaustive. With any study, the user must think
Terminology D1129.
carefully about the factors involved with conducting the
3.2 Definitions of Terms Specific to This Standard:
3.2.1 confidence level, n—theprobabilitythattheprediction
interval from a regression estimate will encompass the true
1
This practice is under the jurisdiction ofASTM Committee D19 on Water and
is the direct responsibility of Subcommittee D19.02 on Quality Systems,
2
Specification, and Statistics. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Dec. 1, 2019. Published January 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2008. Last previous approval in 2013 as D7366 – 08 (2013). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7366-08R19. the ASTM website.
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