Standard Practice for Reporting Results from Methods of Chemical Analysis

SIGNIFICANCE AND USE
A result must be stated to a sufficient number of digits so that a user receives both quantitative information and a measure of the variability of the value reported.
The range of application of most methods of chemical analysis is based upon the presumption that the quantitative results produced are to be used to compare the analyte content of the test material with specified limiting values. However, analytical results may be used legitimately for other purposes. If the same material is analyzed a number of times or a product is analyzed periodically during an interval of production, each set of results may be averaged to yield an average result having improved reliability, provided nothing has been done between analyses to modify the composition of the analyzed material. Results that fall below the lower limit, although not quantitative individually, contain compositional information and may be reported. The reporting system in this practice permits the analyst to indicate which values are likely to be rendered quantitative by averaging and which are not.
The system is simple enough to be used routinely in reporting results from standard methods and assists those untrained in statistics to apply results appropriately.
SCOPE
1.1 This practice covers the approximate number of digits required to express the expected precision of results reported from standard methods of chemical analysis. This practice provides selection criteria and proper form and symbols for coding results when necessary to indicate the relative reliability of results having small values.
1.2 Specifically excluded is consideration of report forms and the associated informational content of reports in which results are tabulated or transmitted. It is assumed that the reporting laboratory has established a report format to ensure proper identification of the materials tested, the nature and conditions of the test, the responsible personnel, and other related information in accordance with existing regulations and good laboratory practices.

General Information

Status
Historical
Publication Date
30-Sep-2010
Current Stage
Ref Project

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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: E1950 − 10
Standard Practice for
1
Reporting Results from Methods of Chemical Analysis
This standard is issued under the fixed designation E1950; 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 3.2.1 lower limit, L, n—the lower limit of the quantitative
analyte concentration range (see Annex A1).
1.1 This practice covers the approximate number of digits
3.2.2 low-level reproducibility index, K ,n—the reproduc-
required to express the expected precision of results reported
R
ibility index constant (for low analyte levels) determined in
from standard methods of chemical analysis. This practice
accordance with Guide E1763.
provides selection criteria and proper form and symbols for
codingresultswhennecessarytoindicatetherelativereliability
3.2.3 null limit, NL, n—the analyte content below which
of results having small values.
results are so near zero that averaging is unlikely to yield a
value significantly different from zero.
1.2 Specifically excluded is consideration of report forms
and the associated informational content of reports in which
3.2.4 quantitative, adj—relating to results,havinganumeri-
results are tabulated or transmitted. It is assumed that the
calvaluethatincludesatleastonesignificantdigit(seePractice
reporting laboratory has established a report format to ensure
E29).
proper identification of the materials tested, the nature and
4. Significance and Use
conditions of the test, the responsible personnel, and other
relatedinformationinaccordancewithexistingregulationsand 4.1 Aresultmustbestatedtoasufficientnumberofdigitsso
good laboratory practices. that a user receives both quantitative information and a
measure of the variability of the value reported.
2. Referenced Documents
4.2 The range of application of most methods of chemical
2
2.1 ASTM Standards:
analysis is based upon the presumption that the quantitative
E29Practice for Using Significant Digits in Test Data to
results produced are to be used to compare the analyte content
Determine Conformance with Specifications
of the test material with specified limiting values. However,
E135Terminology Relating to Analytical Chemistry for
analytical results may be used legitimately for other purposes.
Metals, Ores, and Related Materials
Ifthesamematerialisanalyzedanumberoftimesoraproduct
E1601Practice for Conducting an Interlaboratory Study to
is analyzed periodically during an interval of production, each
Evaluate the Performance of an Analytical Method
setofresultsmaybeaveragedtoyieldanaverageresulthaving
E1763Guide for Interpretation and Use of Results from
improved reliability, provided nothing has been done between
Interlaboratory Testing of Chemical Analysis Methods
analyses to modify the composition of the analyzed material.
3
(Withdrawn 2015)
Results that fall below the lower limit, although not quantita-
tive individually, contain compositional information and may
3. Terminology
be reported. The reporting system in this practice permits the
3.1 Definitions:
analyst to indicate which values are likely to be rendered
3.1.1 For definitions of terms, refer to Terminology E135. quantitative by averaging and which are not.
3.2 Definitions of Terms Specific to This Standard:
4.3 The system is simple enough to be used routinely in
reporting results from standard methods and assists those
untrained in statistics to apply results appropriately.
1
This practice is under the jurisdiction ofASTM Committee E01 on Analytical
ChemistryforMetals,Ores,andRelatedMaterialsandisthedirectresponsibilityof
5. Rounding Calculated Values
Subcommittee E01.22 on Laboratory Quality.
Current edition approved Oct. 1, 2010. Published December 2010. Originally
5.1 Use information from the precision section of the
approved in 1998. Last previous edition approved in 2003 as E1950–98(2003).
method to determine the appropriate number of digits to report
DOI: 10.1520/E1950-10.
2
as follows:
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.1.1 Estimate the reproducibility index, R, at the analyte
Standards volume information, refer to the standard’s Document Summary page on
level of the result, C, from an equation of R as a function of
the ASTM website.
3
concentration or from the table of statistical information.
The last approved version of this historical standard is referenced on
www.astm.org. 5.1.2 Calculate the percent relative reproducibility index:
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. Unite
...

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.
Designation:E1950–98 (Reapproved 2003) Designation:E1950–10
Standard Practice for
1
Reporting Results from Methods of Chemical Analysis
This standard is issued under the fixed designation E1950; 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 covers the approximate number of digits required to express the expected precision of results reported from
standard methods of chemical analysis. This practice provides selection criteria and proper form and symbols for coding results
when necessary to indicate the relative reliability of results having small values.
1.2 Specifically excluded is consideration of report forms and the associated informational content of reports in which results
are tabulated or transmitted. It is assumed that the reporting laboratory has established a report format to ensure proper
identification of the materials tested, the nature and conditions of the test, the responsible personnel, and other related information
in accordance with existing regulations and good laboratory practices.
2. Referenced Documents
2
2.1 ASTM Standards:
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E1601 Practice for Conducting an Interlaboratory Study to Evaluate the Performance of an Analytical Method
E1763 Guide for Interpretation and Use of Results from Interlaboratory Testing of Chemical Analysis Methods
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms, refer to Terminology E135.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 lower limit, L, n—the lower limit of the quantitative analyte concentration range. —the lower limit of the quantitative
analyte concentration range (see Annex A1).
3.2.2 low-level reproducibility index, K , n—the reproducibility index constant (for low analyte levels) determined in
R
accordance with Guide E1763.
3.2.3 null limit, NL, n—the analyte content below which results are so near zero that averaging is unlikely to yield a value
significantly different from zero.
3.2.4 quantitative, adj—relating to results, having a numerical value that includes at least one significant digit (see Practice
E29).
4. Significance and Use
4.1 A result shouldmust be stated to a sufficient number of digits so that a user receives both quantitative information and a
measure of the variability of the value reported.
4.2 The range of application of most methods of chemical analysis is based upon the presumption that the quantitative results
produced are to be used to compare the analyte content of the test material with specified limiting values. However, analytical
results may be used legitimately for other purposes. If the same material is analyzed a number of times or a product is analyzed
periodically during an interval of production, each set of results may be averaged to yield an average result having improved
reliability, provided nothing has been done between analyses to modify the composition of the analyzed material. Results that fall
below the lower limit, although not quantitative individually, contain compositional information and shallmay be reported. The
1
This practice is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility of
Subcommittee E01.22 on Statistics and Quality Control.
Current edition approved Oct. 1, 2003. Published November 2003. Originally approved in 1998. Last previous edition approved in 1998 as E1950–98. DOI:
10.1520/E1950-98R03.on Laboratory Quality.
Current edition approved Oct. 1, 2010. Published December 2010. Originally approved in 1998. Last previous edition approved in 2003 as E1950 – 98 (2003). DOI:
10.1520/E1950-10.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959, United States.
1

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E1950–10
reporting system in this practice permits the analyst to indicate which value
...

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