ASTM E29-93a(1999)
(Practice)Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
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. Reference to this practice is valid only when a choice of method has been indicated, that is, either absolute method or rounding method .
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 This practice describes two commonly accepted methods of rounding data, identified as the Absolute Method and the Rounding Method. In the application 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 is arbitrary, depending upon the current practice of the particular branch of industry or technology concerned, and should therefore be specified in the prime publication.
1.4 Section 7 of this practice gives guidelines for use in recording, calculating, and reporting the final result for test data.
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: E 29 – 93a (Reapproved 1999)
Standard Practice for
Using Significant Digits in Test Data to Determine
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Conformance with Specifications
ThisstandardisissuedunderthefixeddesignationE 29;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (ϵ) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope E 380 Practice for Use of the International System of Units
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(SI) (the Modernized Metric System)
1.1 This practice is intended to assist the various technical
committees in the use of uniform methods of indicating the
3. Terminology
number of digits which are to be considered significant in
3.1 significant digit, n—any of the figures 0 through 9,
specification limits, for example, specified maximum values
excepting leading zeros and some trailing zeros, which is used
and specified minimum values. Its aim is to outline methods
with its place value to denote a numerical quantity to some
which should aid in clarifying the intended meaning of
desired approximation.
specification limits with which observed values or calculated
3.1.1 The digit zero may either indicate a specific value or
test results are compared in determining conformance with
indicate place only. Zeros leading the first nonzero digit of a
specifications. Reference to this practice is valid only when a
number indicate order of magnitude only and are not signifi-
choice of method has been indicated, that is, either absolute
cantdigits.Forexample,thenumber0.0034hastwosignificant
method or rounding method.
digits. Zeros trailing the last nonzero digit for numbers
1.2 This practice is intended to be used in determining
represented with a decimal point are significant digits. For
conformance with specifications when the applicable ASTM
example, the numbers 1270. and 32.00 each have four signifi-
specifications or standards make direct reference to this prac-
cant digits. The significance of trailing zeros for numbers
tice.
represented without use of a decimal point can only be
1.3 This practice describes two commonly accepted meth-
identified from knowledge of the source of the value. For
odsofroundingdata,identifiedastheAbsoluteMethodandthe
example, a modulus strength, stated as 140 000 Pa, may have
Rounding Method. In the application of this practice to a
as few as two or as many as six significant digits.
specific material or materials it is essential to specify which
3.1.2 To eliminate ambiguity, the exponential notation may
method is intended to apply. In the absence of such specifica-
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be used. Thus, 1.40 3 10 indicates that the modulus is
tion, reference to this practice, which expresses no preference
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reported to the nearest 0.01 3 10 or 1000 Pa.
as to which method should apply, would be meaningless. The
3.1.3 Use of appropriate SI prefixes is recommended for
choice of method is arbitrary, depending upon the current
metric units to reduce the need for trailing zeros of uncertain
practice of the particular branch of industry or technology
significance. Thus, 140 kPa and 0.140 MPa each indicate that
concerned, and should therefore be specified in the prime
the modulus is reported to the nearest 1 kPa or 1000 Pa, while
publication.
140 kPa may again have two or three significant digits.
1.4 Section 7 of this practice gives guidelines for use in
recording, calculating, and reporting the final result for test
4. Expression of Numerical Requirements
data.
4.1 The unqualified statement of a numerical limit, such as
2. Referenced Documents “2.50 in. max,” cannot, in view of different established
practices and customs, be regarded as carrying a definite
2.1 ASTM Standards:
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operational meaning concerning the number of digits to be
E 456 Terminology Relating to Quality and Statistics
retained in an observed or a calculated value for purposes of
determining conformance with specifications.
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4.2 Absolute Method—In some fields, specification limits of
ThispracticeisunderthejurisdictionofASTMCommitteeE-11onQualityand
Statistics and is the direct responsibility of Subcommittee E11.10 on Sampling and
2.5 in. max, 2.50 in. max, and 2.500 in. max are all taken to
Data Analysis.
imply the same absolute limit of exactly two and a half inches
Current edition approved March 15, 1993. Published May 1993. Originally
and for purposes of determining conformance with specifica-
published as E 29 – 40. Last previous edition E 29 – 93.
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Annual Book of ASTM Standards, Vol 14.02. tions,anobservedvalueoracalculatedvalueistobecompared
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