ASTM E29-06
(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.
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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An American National Standard
Designation: E 29 – 06
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
a decimal point can only be identified from knowledge of the source of the
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.
conformance with specifications when the applicable ASTM NOTE 3—Use of appropriate SI prefixes is recommended for metric
units to reduce the need for trailing zeros of uncertain significance. Thus,
specifications or standards make direct reference to this prac-
140 kPa and 0.140 MPa each indicate that the modulus is reported to the
tice.
nearest 1 kPa or 1000 Pa, while 140 kPa may again have two or three
1.3 Reference to this practice is valid only when a choice of
significant digits.
method has been indicated, that is, either absolute method or
3.4 test result, n—the value of a characteristic obtained by
rounding method.
carrying out a specified test method. E 2282
2. Referenced Documents
4. Significance and Use
2
2.1 ASTM Standards:
4.1 This practice describes two commonly accepted meth-
E 456 Terminology Relating to Quality and Statistics
odsofroundingdata,identifiedastheAbsoluteMethodandthe
E 2282 Guide for Defining the Test Result of a Test Method
Rounding Method. In the applications of this practice to a
SI 10 Standard for Use of the International System of Units
specific material or materials it is essential to specify which
(SI) (the Modernized Metric System)
method is intended to apply. In the absence of such specifica-
3. Terminology tion, reference to this practice, which expresses no preference
as to which method should apply, would be meaningless. The
3.1 Definitions:
choice of method depends upon the current practice of the
3.2 observed value, n—the value obtained by making an
particular branch of industry or technology concerned, and
observation. E 2282
should therefore be specified in the prime publication.
3.3 significant digit—any of the figures 0 through 9, except-
4.1.1 Theunqualifiedstatementofanumericallimit,suchas
ing leading zeros and some trailing zeros, which is used with
“2.50 in. max,” cannot, in view of different established
its place value to denote a numerical quantity to some desired
practices and customs, be regarded as carrying a definite
approximation.
operational meaning concerning the number of digits to be
retained in an observed or a calculated value for purposes of
1
This practice is under the jurisdiction ofASTM Committee E11 on Quality and
determining conformance with specifications.
Statistics and is the direct responsibility of Subcommittee E11.30 on DataAnalysis.
4.1.2 Absolute Method—In some fields, specification limits
CurrenteditionapprovedMay1,2006.PublishedJuly2006.Originallyapproved
of 2.5 in. max, 2.50 in. max, and 2.500 in. max are all taken to
in 1940. Last previous edition approved in 2004 as E 29 – 04.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
imply the same absolute limit of exactly two and a half inches
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
and for purposes of determining conformance w
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