ASTM E456-02

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Designation:E456–02
Standard Terminology
1
Relating to Quality and Statistics
This standard is issued under the fixed designation E456; 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 (ε) indicates an editorial change since the last revision or reapproval.
NOTE 1—The term accuracy, when applied to a set of test results,
1. Scope
involves a combination of a random component and of a common
1.1 This terminology includes those quality and statistical
systematic error or bias component.
terms in wide use in ASTM for which standard definitions
aliases, n—in a fractional factorial design,twoormoreeffects
appear desirable.
which are estimated by the same contrast and which,
2. Referenced Documents
therefore, cannot be estimated separately. E 1325
assignable cause, n—afactorthatcontributestovariation,and
2.1 ASTM Standards:
which is feasible to detect and identify.
E177 Practice for the Use of the Terms Precision and Bias
2
in ASTM Test Methods
NOTE 2—Many factors will contribute to variation but it may not be
2
E1325 Terminology Relating to Design of Experiments
feasible (economically or otherwise) to identify some of them.
2
E1402 Terminology Relating to Sampling
attribute data, n—observed values or determinations which
3. Significance and Use indicate the presence or absence of specific characteristics.
3.1 Thisterminologyisthegeneralterminologystandardfor
DISCUSSION—Itemsorunitsofmaterialmaybeevaluatedbycounting
terms defined by Committee E-11. or measurement. Attributes are counted whereas variables are mea-
sured. Attribute distributions are discrete. See variables data.
3.2 Citation is made to other E-11 standards which contain
more extensive information regarding the particular term and
attributes, method of, n—measurement of quality by the
its usage. These references may be to other practices and
method of attributes consists of noting the presence (or
guides or to more specific terminology standards, such as
absence) of some characteristic or attribute in each of the
Terminology E1325.
units in the group under consideration, and counting how
many units do (or do not) possess the quality attribute, or
4. Terminology
how many such events occur in the unit, group, or area.
acceptance (control chart or acceptance control chart
average run length (ARL)—(1) sample sense, n—the aver-
usage, n), n—a decision that the process is operating in a
age number of times that a process will have been sampled
satisfactory manner with respect to the statistical measures
and evaluated before a shift in process level is signaled, and
being plotted: action limits: control limits.
(2)unitsense, n—theaveragenumberofunitsthatwillhave
accepted reference value, n—a value that serves as an
been produced before a shift in level is signaled.
agreed-upon reference for comparison, and which is derived
DISCUSSION—A long ARL is desirable for a process located at its
as: (1) a theoretical or established value, based on scientific
specified level (so as to minimize calling for unneeded investigation or
principles, (2) an assigned or certified value, based on
corrective action) and a shortARL is desirable for a process shifted to
experimental work of some national or international organi-
some undesirable level (so that corrective action will be called for
zation, or (3) a consensus or certified value, based on
promptly). ARL curves are used to describe the relative quickness in
detecting level shifts of various control chart systems.
collaborative experimental work under the auspices of a
scientific or engineering group.
balanced incomplete block design (BIB), n—an incomplete
accuracy, n—the closeness of agreement between a test result
block design in which each block contains the same number
and an accepted reference value.
k of different versions from the t versions of a single
principal factor arranged so that every pair of versions
occurs together in the same number, λ, of blocks from the b
1
ThisterminologyisunderthejurisdictionofASTMCommitteeE11onQuality
blocks. E 1325
and Statistics and is the direct responsibility of Subcommittee E11.60 on Terminol-
batch, n—a definite quantity of some product or material
ogy.
Current edition approved Oct. 10, 2002. Published November 2002. Originally
produced under conditions that are considered uniform.
published as E456–72. Last previous edition E456–96.
2
Annual Book of ASTM Standards, Vol 14.02. NOTE 3—A batch is usually smaller than a lot.
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E456–02
bias, n—the difference between the expectation of
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