ASTM D6518-03a
(Practice)Standard Practice for Bias Testing a Mechanical Coal Sampling System
Standard Practice for Bias Testing a Mechanical Coal Sampling System
SCOPE
1.1 This practice presents sample collection and statistical evaluation procedures for testing mechanical sampling systems, subsystems, and individual system components for bias. It is the responsibility of the user of this practice to select the appropriate procedure for a specific sampling situation.
1.2 This practice does not purport to define an absolute bias. Bias defined by this practice is the difference between the population mean of the mechanical sampler test results and the accepted reference value.
1.3 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D 6518 – 03a
Standard Practice for
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Bias Testing a Mechanical Coal Sampling System
This standard is issued under the fixed designation D 6518; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice presents sample collection and statistical 3.1 Definitions—For additional definitions of terms used in
evaluation procedures for testing mechanical sampling sys- this practice refer to Terminologies D 121 and E 456.
tems, subsystems, and individual system components for bias. 3.2 Definitions of Terms Specific to This Standard:
It is the responsibility of the user of this practice to select the 3.2.1 bias, n—the difference between the population mean
appropriate procedure for a specific sampling situation. of the mechanical sampler test results and the accepted
1.2 Thispracticedoes not purport to define an absolutebias. reference value.
Bias defined by this practice is the difference between the 3.2.2 confidence interval, n—a numeric interval with a
population mean of the mechanical sampler test results and the lower limit and a higher limit within which the true parameter
accepted reference value. value is estimated to fall. The confidence interval percentage
1.3 This standard does not purport to address all of the indicates the percentage of time the true value will fall within
safety concerns, if any, associated with its use. It is the the interval if the procedure is continuously repeated.
responsibility of the user of this standard to establish appro- 3.2.3 correlation, n—a measure of the linear dependence
priate safety and health practices and determine the applica- between paired system and reference measurements. Correla-
bility of regulatory limitations prior to use. tion frequently is expressed by the correlation coefficient,
which can take a value from minus one (perfect negative linear
2. Referenced Documents
relationship) to plus one (perfect positive linear relationship).
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2.1 ASTM Standards: 3.2.4 delimitation error, n—a material error that occurs
D 121 Terminology of Coal and Coke
when all the elements in a cross section of a coal stream do not
D 2013 Practice for Preparing Coal Samples for Analysis haveanequalprobabilityofbeingintercepted(captured)bythe
D 2234 Practice for Collection of a Gross Sample of Coal
sampler cutter during increment collection.
D 4621 Guide for Quality Management in an Organization
3.2.5 ellipsoidal region, n—an area that is formed by plane
that Samples or Tests Coal and Coke sections of ellipses that are defined by the values selected for
D 4702 Guide for Inspecting Crosscut, Sweep-Arm, and
the largest tolerable bias of each coal characteristic used in the
Auger Mechanical Coal Sampling Systems for Conform- bias test. The region will be used to determine if the system is
ance with Current ASTM Standards
biased.
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E 105 Practice for Probability Sampling of Materials 3.2.6 Hotelling’s T test, n—a statistical test that is used to
E 122 Practice for Calculating Sample Size to Estimate,
evaluate multivariate data. It is the multivariate equivalent of
with a Specified Tolerable Error, the Average for a Char- the Student’s t-test.
acteristic of a Lot or Process
3.2.7 largest tolerable bias (LTB), n—an interval whose
E 456 Terminology Relating to Quality and Statistics upper and lower bounds represent the limits of an acceptable
E 691 Practice for Conducting an Interlaboratory Study to
bias.
Determine the Precision of a Test Method 3.2.8 mechanical sampling system, n—a single machine or
series of interconnected machines whose purpose is to extract
mechanically, or process (divide and reduce), or a combination
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This practice is under the jurisdiction of ASTM Committee D05 on Coal and
thereof, a sample of coal.
Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.
3.2.9 paired data set, n—system and reference values ob-
Current edition approved Dec. 1, 2003. Published January 2004.Originally
approved in 2000. Last previous edition approved in 2003 as D 6518–03. servedonsamplescollectedandcomparedfromthesamebatch
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
of material.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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D 6518 – 03a
3.2.10 reference sample, n—a sample used in testing of a param
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