ASTM E29-06b
(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
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. 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. Two commonly accepted methods of rounding data, identified as the absolute method and the rounding method are described. The guidelines for retaining significant figures in calculation and reporting of test results are presented in details.
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.
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Standards Content (Sample)
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An American National Standard
Designation: E 29 – 06b
Standard Practice for
Using Significant Digits in Test Data to Determine
1
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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
NOTE 1—The digit zero may either indicate a specific value or indicate
1. Scope*
place only. Zeros leading the first nonzero digit of a number indicate order
1.1 This practice is intended to assist the various technical
of magnitude only and are not significant digits. For example, the number
committees in the use of uniform methods of indicating the
0.0034 has two significant digits. Zeros trailing the last nonzero digit for
number of digits which are to be considered significant in
numbers represented with a decimal point are significant digits. For
specification limits, for example, specified maximum values example, the numbers 1270. and 32.00 each have four significant digits.
The significance of trailing zeros for numbers represented without use of
and specified minimum values. Its aim is to outline methods
adecimalpointcanonlybeidentifiedfromknowledgeofthesourceofthe
which should aid in clarifying the intended meaning of
value. For example, a modulus strength, stated as 140 000 Pa, may have
specification limits with which observed values or calculated
as few as two or as many as six significant digits.
test results are compared in determining conformance with
NOTE 2—To eliminate ambiguity, the exponential notation may be
5
specifications.
used. Thus, 1.40 3 10 indicates that the modulus is reported to the
5
1.2 This practice is intended to be used in determining
nearest 0.01 3 10 or 1000 Pa.
NOTE 3—Use of appropriate SI prefixes is recommended for metric
conformance with specifications when the applicable ASTM
units to reduce the need for trailing zeros of uncertain significance. Thus,
specifications or standards make direct reference to this prac-
140 kPa (without the decimal point) indicates that the modulus is reported
tice.
either to the nearest 10 or 1 kPa, which is ambiguous with respect to the
1.3 Reference to this practice is valid only when a choice of
number of significant digits. However, 0.140 MPa clearly indicates that
method has been indicated, that is, either absolute method or
the modulus is reported to the nearest 1 kPa, and 0.14 MPa clearly
rounding method.
indicates that the modulus is reported to the nearest 10 kPa.
3.4 test result, n—the value of a characteristic obtained by
2. Referenced Documents
carrying out a specified test method. E 2282
2
2.1 ASTM Standards:
E 456 Terminology Relating to Quality and Statistics
4. Significance and Use
E 2282 Guide for Defining the Test Result of a Test Method
4.1 This practice describes two commonly accepted meth-
SI 10 Standard for Use of the International System of Units
odsofroundingdata,identifiedastheAbsoluteMethodandthe
(SI) (the Modernized Metric System)
Rounding Method. In the applications of this practice to a
specific material or materials it is essential to specify which
3. Terminology
method is intended to apply. In the absence of such specifica-
3.1 Definitions:
tion, reference to this practice, which expresses no preference
3.2 observed value, n—the value obtained by making an
as to which method should apply, would be meaningless. The
observation. E 2282
choice of method depends upon the current practice of the
3.3 significant digit—any of the figures 0 through 9, except-
particular branch of industry or technology concerned, and
ing all leading zeros and some trailing zeros in numbers not
should therefore be specified in the prime publication.
represented with a decimal point, which is used with its place
4.1.1 Theunqualifiedstatementofanumericallimit,suchas
value to denote a numerical quantity to some desired approxi-
“2.50 in. max,” cannot, in view of different established
mation.
practices and customs, be regarded as carrying a definite
operational meaning concerning the number of digits to be
1
This practice is under the jurisdiction ofASTM Committee E11 on Quality and retained in an observed or a calculated value for purposes of
Statistics and is the direct responsibility of Subcommittee E11.30 on DataAnalysis.
determining conformance with specifications.
Current edition approved Nov. 15, 2006. Published December 2006. Originally
4.1.2 Absolute Method—In some fields, specification limits
approved in 1940. Last previous edition approved in 2006 as E 29 – 06a.
2
of 2.5 in. max, 2.50 in. max, and 2.500 in. max are all taken to
For re
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