ASTM E29-22

Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications

ABSTRACT
This practice is intended to assist the various technical committees in the use of uniform methods of indicating the number of digits which are to be considered significant in specification limits, for example, specified maximum values and specified minimum values. This practice is also intended to be used in determining conformance with specifications when the applicable ASTM specifications or standards make a direct reference.
SCOPE
1.1 This practice is intended to assist the various technical committees in the use of uniform methods of indicating the number of digits which are to be considered significant in specification limits, for example, specified maximum values and specified minimum values. Its aim is to outline methods which should aid in clarifying the intended meaning of specification limits with which observed values or calculated test results are compared in determining conformance with specifications.  
1.2 This practice is intended to be used in determining conformance with specifications when the applicable ASTM specifications or standards make direct reference to this practice.  
1.3 Reference to this practice is valid only when a choice of method has been indicated, that is, either absolute method or rounding method.  
1.4 The system of units for this practice is not specified. Dimensional quantities in the practice are presented only as illustrations of calculation methods. The examples are not binding on products or test methods treated.  
1.5 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.  
1.6 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

• Status: Published
• Publication Date: 31-Mar-2022
• ICS: 17.020 - Metrology and measurement in general
• ICS: 19.020 - Test conditions and procedures in general
• Technical Committee: E11 - Quality and Statistics
• Drafting Committee: E11.30 - Statistical Quality Control

Relations

• Refers: ASTM E2282-23 - Standard Guide for Defining the Test Result of a Test Method
• Effective Date: 01-Nov-2023
• Refers: ASTM E456-13a(2022)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Apr-2022
• Refers: ASTM E456-13A(2017)e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E456-13A(2017)e3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-Oct-2017
• Refers: ASTM E2282-14 - Standard Guide for Defining the Test Result of a Test Method
• Effective Date: 01-Oct-2014
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E456-13ae2 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013
• Refers: ASTM E456-13ae1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013
• Refers: ASTM E456-13a - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013
• Refers: ASTM E456-13ae3 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Nov-2013
• Refers: ASTM E456-13 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 15-Aug-2013
• Refers: ASTM E2282-13 - Standard Guide for Defining the Test Result of a Test Method
• Effective Date: 01-Aug-2013
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E456-12e1 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-May-2012
• Refers: ASTM E456-12 - Standard Terminology Relating to Quality and Statistics
• Effective Date: 01-May-2012

Overview

ASTM E29-22: Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications provides essential guidelines for the use of significant digits when establishing and evaluating specification limits in test data. Developed and maintained by ASTM International, this standard ensures consistency and clarity in the presentation of numerical limits, supporting the accurate determination of product or material conformance. ASTM E29-22 assists technical committees, laboratories, and industries in utilizing uniform methods for identifying significant digits, thus minimizing misinterpretation and ambiguity when compared to established specifications.

Key Topics

• Significant Digits Definition: This standard clarifies what constitutes a significant digit in test results and how these should be identified and reported, eliminating confusion regarding trailing or leading zeros and their implications in measurement precision.
• Conformance Methods: Two primary methods for assessing conformance using significant digits are covered:
  • Absolute Method: All digits in observed or calculated values are considered significant, and direct comparison is made to the specified limit.
  • Rounding Method: Observed or calculated values are rounded to a designated level before comparison, based on the number of digits in the specification.
• Guidelines for Reporting: Proper procedures for recording, calculating, and reporting test data are established, ensuring that the significant digits retained align with the precision of the measurement technique and the requirements of the specification.
• Calculation Rules: The standard details specific approaches for addition, subtraction, multiplication, division, and logarithmic/exponential operations so that the correct number of significant digits is maintained in computed results.
• Customization: The standard emphasizes the need for each specification or standard to specify which conformance method is used (absolute or rounding) for clarity and meaningful application.

Applications

ASTM E29-22 finds wide use across numerous industries and laboratories where compliance with product or material specifications is critical. Key applications include:

• Material Testing Laboratories: Ensuring consistent use of significant digits when presenting and evaluating results, whether for metals, plastics, or composite materials.
• Quality Control: Supporting companies in accurately determining pass/fail status by correctly interpreting specification limits and minimizing errors due to rounding or misreporting figures.
• Technical Standards Development: Assisting ASTM committees and other standards organizations in drafting clear and unambiguous specification limits for both maximum and minimum values.
• Manufacturing: Helping manufacturers avoid disputes and non-conformance by providing clear rules for data reporting relative to specification precision.
• Statistical Analysis: Enabling robust statistical treatment and comparability of test data through uniform practices in significant digit retention and rounding.

Related Standards

ASTM E29-22 is supported by and often referenced alongside several other key standards in the context of quality, statistics, and measurement, including:

• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E456: Terminology Relating to Quality and Statistics
• ASTM E2282: Guide for Defining the Test Result of a Test Method
• IEEE/ASTM SI 10: Standard for Use of the International System of Units (SI)

These related standards provide further guidance on precision, statistical terminology, test method results definition, and proper use of SI units, collectively contributing to a comprehensive framework for measurement, reporting, and compliance assessment.

Practical Value

By adopting ASTM E29-22, organizations ensure accuracy, repeatability, and consistency in conformance assessments, minimize the risk of misinterpretation of specifications, and improve confidence in reported test results. The standard’s clear methodologies for significant digit usage make it an invaluable reference in quality management systems, technical documentation, and compliance verification in regulated industries.

Keywords: ASTM E29-22, significant digits, conformance, specification limits, rounding method, absolute method, test data, quality control, reporting standards, measurement precision.

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:E29 −22 An American National Standard
Standard Practice for
Using Significant Digits in Test Data to Determine
Conformance with Specifications
ThisstandardisissuedunderthefixeddesignationE29;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This practice is intended to assist the various technical
E177Practice for Use of the Terms Precision and Bias in
committees in the use of uniform methods of indicating the
ASTM Test Methods
number of digits which are to be considered significant in
E456Terminology Relating to Quality and Statistics
specification limits, for example, specified maximum values
E2282Guide for Defining the Test Result of a Test Method
and specified minimum values. Its aim is to outline methods
IEEE/ASTMSI10American National Standard for Metric
which should aid in clarifying the intended meaning of
Practice
specification limits with which observed values or calculated
test results are compared in determining conformance with
3. Terminology
specifications.
3.1 Definitions—Terminology E456 provides a more exten-
1.2 This practice is intended to be used in determining
sive list of terms in E11 standards.
conformance with specifications when the applicable ASTM
3.1.1 observed value, n—the value obtained by making an
specifications or standards make direct reference to this prac-
observation. E2282
tice.
3.1.2 repeatability conditions, n—conditions where inde-
1.3 Referencetothispracticeisvalidonlywhenachoiceof
pendent test results are obtained with the same method on
method has been indicated, that is, either absolute method or
identicaltestitemsinthesamelaboratorybythesameoperator
rounding method.
using the same equipment within short intervals of time. E177
1.4 The system of units for this practice is not speci-
3.1.3 repeatability standard deviation (s ), n—the standard
r
fied. Dimensional quantities in the practice are presented only
deviation of test results obtained under repeatability
as illustrations of calculation methods. The examples are not
conditions. E177
binding on products or test methods treated.
3.1.4 significant digit—any of the figures 0 through 9 that is
1.5 This standard does not purport to address all of the
used with its place value to denote a numerical quantity to
safety concerns, if any, associated with its use. It is the
some desired approximation, excepting all leading zeros and
responsibility of the user of this standard to establish appro-
some trailing zeros in numbers not represented with a decimal
priate safety, health, and environmental practices and deter-
point.
mine the applicability of regulatory limitations prior to use.
3.1.4.1 Discussion—This definition of significant digits re-
1.6 This international standard was developed in accor- lates to how the number is represented as a decimal. It should
dance with internationally recognized principles on standard- not be inferred that a measurement value is precise to the
ization established in the Decision on Principles for the number of significant digits used to represent it.
Development of International Standards, Guides and Recom- 3.1.4.2 Discussion—The digit zero may either indicate a
mendations issued by the World Trade Organization Technical specific value or indicate place only. Zeros leading the first
Barriers to Trade (TBT) Committee. nonzerodigitofanumberindicateorderofmagnitudeonlyand
are not significant digits. For example, the number 0.0034 has
two significant digits. Zeros trailing the last nonzero digit for
ThispracticeisunderthejurisdictionofASTMCommitteeE11onQualityand
Statistics and is the direct responsibility of Subcommittee E11.30 on Statistical
Quality Control. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved April 1, 2022. Published April 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approvedin1940.Lastpreviouseditionapprovedin2019asE29–13(2019).DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E0029-22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E29−22
numbersrepresentedwithadecimalpointaresignificantdigits. This will be referred to as the rounding method, which is
For example, the numbers 1270. and 32.00 each have four discussed in Section 7.
significantdigits.Thesignificanceoftrailingzerosfornumbers
4.4 Section 8 of this practice gives guidelines for use in
represented without use of a decimal point can only be
recording, calculating, and reporting the final result for test
identified from knowledge of the source of the value. For
data.
example, a modulus strength, stated as 140000 Pa, may have
as few as two or as many as six significant digits.
5. Treatment of Test Results
3.1.4.3 Discussion—To eliminate ambiguity, the exponen-
5.1 Bias adjustments to be applied and criteria for accept-
tial notation may be used. Thus, 1.40×10 indicates that the
ability of the test data should be specified in the test method.
modulus is reported to the nearest 0.01×10 or 1000 Pa.
3.1.4.4 Discussion—Use of appropriate SI prefixes is rec-
5.2 Unless permitted by the specification or agreed by
ommendedformetricunitstoreducetheneedfortrailingzeros
supplier and receiver, the observed or calculated value for
of uncertain significance. Thus, 140 kPa (without the decimal
comparison to limits shall not be modified in consideration of
point) indicates that the modulus is reported either to the
measurement uncertainty prior to or subsequent to use of the
nearest 10 or 1 kPa, which is ambiguous with respect to the
absolute or rounding method in this standard. When adjust-
number of significant digits. However, 0.140 MPa clearly
ments to the observed or calculated value for comparison to
indicates that the modulus is reported to the nearest 1 kPa, and
specification based on measurement uncertainty are permitted,
0.14 MPa clearly indicates that the modulus is reported to the
thenon-adjustedvalue,adjustedvalue,andadjustmentmethod
nearest 10 kPa.
shall be reported.
3.1.5 test result, n—thevalueofacharacteristicobtainedby
5.3 Unless part of a retest that is compliant with applicable
carrying out a specified test method. E2282
guidelinesandispermittedbythespecification,testmethod,or
a laboratory procedure, the test result for comparison to
4. Significance and Use
specifications shall not be selected among multiple test results
4.1 A test result is compared to specification limits to
of equal validity or repeat testing until a passing value is
determine conformance with the specification. The test result
obtained.
may be an observed value, calculated from two or more
property measurements, or a summary value of multiple test
6. Absolute Method
determinations as defined in the test method.
6.1 Where Applicable—The absolute method applies where
4.2 The unqualified statement of a numerical limit, such as
itistheintentthatalldigitsinanobservedvalueoracalculated
“2.50 in. max,” cannot, in view of different established
value are to be considered significant for purposes of deter-
practices and customs, be regarded as carrying a definite
mining conformance with specifications. Under these
operational meaning concerning the number of digits to be
conditions, the specified limits are referred to as absolute
retained in an observed or a calculated value for purposes of
limits.
determining conformance with specifications.
6.2 How Applied—With the absolute method, an observed
4.3 This practice describes two commonly accepted meth-
value or a calculated value is not to be rounded, but is to be
ods to evaluate conformance of a numerical value to
compared directly with the specified limiting value. Confor-
specification, identified as the Absolute Method and the
mance or nonconformance with the specification is based on
Rounding Method. In the applications of this practice to a
this comparison.
specific material or materials it is essential to specify which
6.3 How Expressed—This intent may be expressed in the
method is intended to apply. The choice of method depends
standard in one of the following forms:
uponthecurrentpracticeoftheparticularbranchofindustryor
6.3.1 Iftheabsolutemethodistoapplytoallspecifiedlimits
technology concerned, and should therefore be specified in the
in the standard, this may be indicated by including the
prime publication.
following sentence in the standard:
4.3.1 Absolute Method—In some fields, specification limits
of 2.5 in. max, 2.50 in. max, and 2.500 in. max are all taken to For purposes of determining conformance with these specifications, all
specified limits in this standard are absolute limits, as defined in ASTM Practice
imply the same absolute limit of exactly two and a half inches
E29, for Using Significant Digits in Test Data to Determine Conformance with
and for purposes of determining conformance with
Specifications.
specifications, an observed value or a calculated value is to be
6.3.2 Iftheabsolutemethodistoapplytoallspecifiedlimits
compareddirectlywiththespecifiedlimit.Thus,anydeviation,
of some general type in the standard (such as dimensional
howeversmall,outsidethespecificationlimitsignifiesnoncon-
tolerance limits), this may be indicated by including the
formancewiththespecifications.Thiswillbereferredtoasthe
following sentence in the standard:
absolute method, which is discussed in Section 6.
For purposes of determining conformance with these specifications, all
4.3.2 Rounding Method—Inotherfields,specificationlimits
specified (dimensional tolerance) limits are absolute limits, as defined in ASTM
of 2.5 in. max, 2.50 in. max, and 2.500 in. max are taken to
Practice E29, for Using Significant Digits in Test Data to Determine Confor-
mance with Specifications.
imply that, for the purposes of determining conformance with
specifications, an observed value or a calculated value should 6.3.3 Iftheabsolutemethodistoapplytoallspecifiedlimits
be rounded to the nearest 0.1 in., 0.01 in., 0.001 in., given in a table, this may be indicated by including a footnote
respectively, and then compared with the specification limit. with the table as follows:
E29−22
A
Capacity Chemical Composition,
Volumetric Tolerance
mL ±mL % mass
10 0.02 Copper 4.5 ± 0.5
25 0.03 Iron 1.0 max
50 0.05 Silicon 2.5 ± 0.5
100 0.10 Other constituents (magnesium + zinc + manganese) 0.5 max
Aluminum remainder
A
TolerancelimitsspecifiedareabsolutelimitsasdefinedinPracticeE29,forUsing For purposes of determining conformance with these specifications, an
observed value or a calculated value shall be rounded to the nearest 0.1
Significant Digits in Test Data to Determine Conformance with Specifications.
percent, in accordance with the rounding method of ASTM Practice E29 Using
Significant Digits in Test Data to Determine Conformance with Specifications.
7. Rounding Method
7.3.3.2 Example 2—Significant digits not the same for all
7.1 Where Applicable—Theroundingmethodapplieswhere
items; similar requirements:
it is the intent that a limited number of digits in an observed
Chemical Composition, % mass
value or a calculated value are to be considered significant for min max
purposes of determining conformance with specifications.
Nickel 57 .
Chromium 14 18
7.2 How Applied—With the rounding method, an observed
Manganese . 3
value or a calculated value is rounded by the procedure
Silicon . 0.40
Carbon . 0.25
prescribed in 7.4 to the nearest unit in the designated place of
Sulfur . 0.03
figures stated in the standard. The rounded value is compared
Iron remainder
with the specified limit, and conformance or nonconformance
For purposes of determining conformance with these specifications, an
with the specification based on this comparison.
observed value or a calculated value shall be rounded “to the nearest unit” in
the last right-hand significant digit used in expressing the limiting value, in
7.2.1 The value as rounded to the decimal places of the
accordance with the rounding method of ASTM Practice E29 Using Significant
specification is not required to be the reported value. Addi-
Digits in Test Data to Determine Conformance with Specifications.
tionalfiguresmaybeprovidedtopreserveinformation,andthe
7.3.3.3 Example 3—Significant digits not the same for all
rounding left implicit (see 8.1). For example, report passing
items; dissimilar requirements:
observed or calculated values 0.012 or 0.0003 rather than 0.01
Tensile Requirements
or 0.00 for specification “not more than 0.01,” or values
Tensile strength, psi 60 000 to 72 000
98.65% or 99.97% rather than 99% or 100% for specifica-
Yield point, min, psi 33 000
tion ≥99%. A test method may also specify the decimals in
Elongation in 2 in., min % 22
values to be reported.
For purposes of determination of conformance with these specifications, an
observed value or a calculated value shall be rounded to the nearest 1000 psi
7.3 How Expressed—This intent may be expressed in the
for tensile strength and yield point and to the nearest 1 percent for elongation,
standard in one of the following forms:
in accordance with the rounding method of ASTM Practice E29 Using Signifi-
cant Digits in Test Data to Determine Conformance with Specifications.
7.3.1 If the rounding method is to apply to all specified
7.4 Rounding Procedure—The actual rounding procedure
limits in the standard, and if all digits expressed in the
shall be as follows:
specification limit are to be considered significant, this may be
7.4.1 When the digit next beyond the last place to be
indicated by including the following statement in the standard:
retained is less than 5, retain unchanged the digit in the last
The following applies to all specified limits in this standard: For purposes of
place retained.
determining conformance with these specifications, an observed value or a
calculated val
...

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: E29 − 13 (Reapproved 2019) E29 − 22 An American National Standard
Standard Practice for
Using Significant Digits in Test Data to Determine
Conformance with Specifications
This standard is issued under the fixed designation E29; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This practice is intended to assist the various technical committees in the use of uniform methods of indicating the number
of digits which are to be considered significant in specification limits, for example, specified maximum values and specified
minimum values. Its aim is to outline methods which should aid in clarifying the intended meaning of specification limits with
which observed values or calculated test results are compared in determining conformance with specifications.
1.2 This practice is intended to be used in determining conformance with specifications when the applicable ASTM specifications
or standards make direct reference to this practice.
1.3 Reference to this practice is valid only when a choice of method has been indicated, that is, either absolute method or rounding
method.
1.4 The system of units for this practice is not specified. Dimensional quantities in the practice are presented only as illustrations
of calculation methods. The examples are not binding on products or test methods treated.
1.5 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.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E456 Terminology Relating to Quality and Statistics
E2282 Guide for Defining the Test Result of a Test Method
IEEE/ASTM SI 10 Standard for Use of the International System of Units (SI): The Modern Metric SystemAmerican National
Standard for Metric Practice
This practice is under the jurisdiction of ASTM Committee E11 on Quality and Statistics and is the direct responsibility of Subcommittee E11.30 on Statistical Quality
Control.
Current edition approved Jan. 1, 2019April 1, 2022. Published January 2019April 2022. Originally approved in 1940. Last previous edition approved in 20132019 as
E29 – 13.E29 – 13 (2019). DOI: 10.1520/E0029-13R19.10.1520/E0029-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. 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, PA 19428-2959. United States
E29 − 22
3. Terminology
3.1 Definitions—Terminology E456 provides a more extensive list of terms in E11 standards.
3.1.1 observed value, n—the value obtained by making an observation. E2282
3.1.2 repeatability conditions, n—conditions where independent test results are obtained with the same method on identical test
items in the same laboratory by the same operator using the same equipment within short intervals of time. E177
3.1.3 repeatability standard deviation (s ), n—the standard deviation of test results obtained under repeatability conditions. E177
r
3.1.4 significant digit—any of the figures 0 through 9 that is used with its place value to denote a numerical quantity to some
desired approximation, excepting all leading zeros and some trailing zeros in numbers not represented with a decimal point.
3.1.4.1 Discussion—
This definition of significant digits relates to how the number is represented as a decimal. It should not be inferred that a
measurement value is precise to the number of significant digits used to represent it.
3.1.4.2 Discussion—
The digit zero may either indicate a specific value or indicate place only. Zeros leading the first nonzero digit of a number indicate
order of magnitude only and are not significant digits. For example, the number 0.0034 has two significant digits. Zeros trailing
the last nonzero digit for numbers represented with a decimal point are significant digits. For example, the numbers 1270. and
32.00 each have four significant digits. The significance of trailing zeros for numbers represented without use of a decimal point
can only be identified from knowledge of the source of the value. For example, a modulus strength, stated as 140 000 Pa, may have
as few as two or as many as six significant digits.
3.1.4.3 Discussion—
To eliminate ambiguity, the exponential notation may be used. Thus, 1.40 × 10 indicates that the modulus is reported to the nearest
0.01 × 10 or 1000 Pa.
3.1.4.4 Discussion—
Use of appropriate SI prefixes is recommended for metric units to reduce the need for trailing zeros of uncertain significance. Thus,
140 kPa (without the decimal point) indicates that the modulus is reported either to the nearest 10 or 1 kPa, which is ambiguous
with respect to the number of significant digits. However, 0.140 MPa clearly indicates that the modulus is reported to the nearest
1 kPa, and 0.14 MPa clearly indicates that the modulus is reported to the nearest 10 kPa.
3.1.5 test result, n—the value of a characteristic obtained by carrying out a specified test method. E2282
4. Significance and Use
4.1 A test result is compared to specification limits to determine conformance with the specification. The test result may be an
observed value, calculated from two or more property measurements, or a summary value of multiple test determinations as defined
in the test method.
4.2 The unqualified statement of a numerical limit, such as “2.50 in. max,” cannot, in view of different established practices and
customs, be regarded as carrying a definite operational meaning concerning the number of digits to be retained in an observed or
a calculated value for purposes of determining conformance with specifications.
4.3 This practice describes two commonly accepted methods of rounding data, to evaluate conformance of a numerical value to
specification, identified as the Absolute Method and the Rounding Method. In the applications of this practice to a specific material
or materials it is essential to specify which method is intended to apply. In the absence of such specification, reference to this
practice, which expresses no preference as to which method should apply, would be meaningless. The choice of method depends
upon the current practice of the particular branch of industry or technology concerned, and should therefore be specified in the
prime publication.
4.1.1 The unqualified statement of a numerical limit, such as “2.50 in. max,” cannot, in view of different established practices and
customs, be regarded as carrying a definite operational meaning concerning the number of digits to be retained in an observed or
a calculated value for purposes of determining conformance with specifications.
4.3.1 Absolute Method—In some fields, specification limits of 2.5 in. max, 2.50 in. max, and 2.500 in. max are all taken to imply
the same absolute limit of exactly two and a half inches and for purposes of determining conformance with specifications, an
E29 − 22
observed value or a calculated value is to be compared directly with the specified limit. Thus, any deviation, however small, outside
the specification limit signifies nonconformance with the specifications. This will be referred to as the absolute method, which is
discussed in Section 56.
4.3.2 Rounding Method—In other fields, specification limits of 2.5 in. max, 2.50 in. max, and 2.500 in. max are taken to imply
that, for the purposes of determining conformance with specifications, an observed value or a calculated value should be rounded
to the nearest 0.1 in., 0.01 in., 0.001 in., respectively, and then compared with the specification limit. This will be referred to as
the rounding method, which is discussed in Section 67.
4.4 Section 78 of this practice gives guidelines for use in recording, calculating, and reporting the final result for test data.
5. Treatment of Test Results
5.1 Bias adjustments to be applied and criteria for acceptability of the test data should be specified in the test method.
5.2 Unless permitted by the specification or agreed by supplier and receiver, the observed or calculated value for comparison to
limits shall not be modified in consideration of measurement uncertainty prior to or subsequent to use of the absolute or rounding
method in this standard. When adjustments to the observed or calculated value for comparison to specification based on
measurement uncertainty are permitted, the non-adjusted value, adjusted value, and adjustment method shall be reported.
5.3 Unless part of a retest that is compliant with applicable guidelines and is permitted by the specification, test method, or a
laboratory procedure, the test result for comparison to specifications shall not be selected among multiple test results of equal
validity or repeat testing until a passing value is obtained.
6. Absolute Method
6.1 Where Applicable—The absolute method applies where it is the intent that all digits in an observed value or a calculated value
are to be considered significant for purposes of determining conformance with specifications. Under these conditions, the specified
limits are referred to as absolute limits.
6.2 How Applied—With the absolute method, an observed value or a calculated value is not to be rounded, but is to be compared
directly with the specified limiting value. Conformance or nonconformance with the specification is based on this comparison.
6.3 How Expressed—This intent may be expressed in the standard in one of the following forms:
6.3.1 If the absolute method is to apply to all specified limits in the standard, this may be indicated by including the following
sentence in the standard:
For purposes of determining conformance with these specifications, all
specified limits in this standard are absolute limits, as defined in ASTM Practice
E29, for Using Significant Digits in Test Data to Determine Conformance with
Specifications.
6.3.2 If the absolute method is to apply to all specified limits of some general type in the standard (such as dimensional tolerance
limits), this may be indicated by including the following sentence in the standard:
For purposes of determining conformance with these specifications, all
specified (dimensional tolerance) limits are absolute limits, as defined in ASTM
Practice E29, for Using Significant Digits in Test Data to Determine Confor-
mance with Specifications.
6.3.3 If the absolute method is to apply to all specified limits given in a table, this may be indicated by including a footnote with
the table as follows:
E29 − 22
A
Capacity
Volumetric Tolerance
mL ± mL
10 0.02
25 0.03
50 0.05
100 0.10
A
Tolerance limits specified are absolute limits as defined in Practice E29, for Using Significant Digits in Test Data to Determine Conformance with Specifications.
7. Rounding Method
7.1 Where Applicable—The rounding method applies where it is the intent that a limited number of digits in an observed value
or a calculated value are to be considered significant for purposes of determining conformance with specifications.
7.2 How Applied—With the rounding method, an observed value or a calculated value should be is rounded by the procedure
prescribed in 4.1.37.4 to the nearest unit in the designated place of figures stated in the standard, as, for example, “to the nearest
kPa,” “to the nearest 10 ohms,” “to the nearest 0.1 percent,” etc. standard. The rounded value should then be is compared with
the specified limit, and conformance or nonconformance with the specification based on this comparison.
7.2.1 The value as rounded to the decimal places of the specification is not required to be the reported value. Additional figures
may be provided to preserve information, and the rounding left implicit (see 8.1). For example, report passing observed or
calculated values 0.012 or 0.0003 rather than 0.01 or 0.00 for specification “not more than 0.01,” or values 98.65 % or 99.97 %
rather than 99 % or 100 % for specification ≥99 %. A test method may also specify the decimals in values to be reported.
7.3 How Expressed—This intent may be expressed in the standard in one of the following forms:
7.3.1 If the rounding method is to apply to all specified limits in the standard, and if all digits expressed in the specification limit
are to be considered significant, this may be indicated by including the following statement in the standard:
The following applies to all specified limits in this standard: For purposes of
determining conformance with these specifications, an observed value or a
calculated value shall be rounded “to the nearest unit” in the last right-hand digit
used in expressing the specification limit, in accordance with the rounding
method of ASTM Practice E29, for Using Significant Digits in Test Data to Deter-
mine Conformance with Specifications.
7.3.2 If the rounding method is to apply only to the specified limits for certain selected requirements, this may be indicated by
including the following statement in the standard:
The following applies to specified limits for requirements on (tensile
strength), (elongation), and ( . ) given in ., (applicable section number and
title) and ( . ) of this standard: For purposes of determining conformance with
these specifications, an observed value or a calculated value shall be rounded
to the nearest 1 kPa for (tensile strength), to the nearest (1 percent) for
(elongation), and to the nearest ( . ) for ( . ) in accordance with the rounding
method of ASTM Practice E29 Using Significant Digits in Test Data to Deter-
mine Conformance with Specifications.
7.3.3 If the rounding method is to apply to all specified limits in a table, this may be indicated by a note in the manner shown
in the following examples:
7.3.3.1 Example 1—Same significant digits for all items:
Chemical Composition,
% mass
Copper 4.5 ± 0.5
Iron 1.0 max
Silicon 2.5 ± 0.5
Other constituents (magnesium + zinc + manganese) 0.5 max
Aluminum remainder
E29 − 22
For purposes of determining conformance with these specifications, an
observed value or a calculated value shall be rounded to the ne
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