ASTM D6518-03

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.

General Information

• Status: Historical
• Publication Date: 09-Jun-2002
• ICS: 73.040 - Coals
• Technical Committee: D05 - Coal and Coke
• Drafting Committee: D05.23 - Sampling

Relations

• Replaces: ASTM D6518-02a - Standard Practice for Bias Testing a Mechanical Coal Sampling System
• Effective Date: 10-Jun-2002
• Replaced By: ASTM D6518-03a - Standard Practice for Bias Testing a Mechanical Coal Sampling System
• Effective Date: 01-Dec-2003
• Referred By: ASTM D7430/D7430M-22 - Standard Practice for Mechanical Sampling of Coal
• Effective Date: 10-Jun-2002
• Referred By: ASTM D6543-20e1 - Standard Guide to the Evaluation of Measurements Made by Online Coal Analyzers
• Effective Date: 10-Jun-2002

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6518 – 03
Standard Practice for
1
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 3.2 Definitions of Terms Specific to This Standard:
3.2.1 bias, n—the difference between the population mean
1.1 This practice presents sample collection and statistical
of the mechanical sampler test results and the accepted
evaluation procedures for testing mechanical sampling sys-
reference value.
tems, subsystems, and individual system components for bias.
3.2.2 confidence interval, n—a numeric interval with a
It is the responsibility of the user of this practice to select the
lower limit and a higher limit within which the true parameter
appropriate procedure for a specific sampling situation.
value is estimated to fall. The confidence interval percentage
1.2 This practice does not purport to define an absolute bias.
indicates the percentage of time the true value will fall within
Bias defined by this practice is the difference between the
the interval if the procedure is continuously repeated.
population mean of the mechanical sampler test results and the
3.2.3 correlation, n—a measure of the linear dependence
accepted reference value.
between paired system and reference measurements. Correla-
1.3 This standard does not purport to address all of the
tion frequently is expressed by the correlation coefficient,
safety concerns, if any, associated with its use. It is the
which can take a value from minus one (perfect negative linear
responsibility of the user of this standard to establish appro-
relationship) to plus one (perfect positive linear relationship).
priate safety and health practices and determine the applica-
3.2.4 delimitation error, n—a material error that occurs
bility of regulatory limitations prior to use.
when all the elements in a cross section of a coal stream do not
2. Referenced Documents
have an equal probability of being intercepted (captured) by the
sampler cutter during increment collection.
2.1 ASTM Standards:
2
3.2.5 ellipsoidal region, n—an area that is formed by plane
D 121 Terminology of Coal and Coke
2
sections of ellipses that are defined by the values selected for
D 2013 Practice for Preparing Coal Samples for Analysis
2
the largest tolerable bias of each coal characteristic used in the
D 2234 Practice for Collection of a Gross Sample of Coal
bias test. The region will be used to determine if the system is
D 4621 Guide for Quality Management in an Organization
2
biased.
that Samples or Tests Coal and Coke
2
3.2.6 Hotelling’s T test, n—a statistical test that is used to
D 4702 Guide for Inspecting Crosscut, Sweep-Arm, and
evaluate multivariate data. It is the multivariate equivalent of
Auger Mechanical Coal Sampling Systems for Conform-
2
the Student’s t-test.
ance with Current ASTM Standards
3
3.2.7 largest tolerable bias (LTB), n—an interval whose
E 105 Practice for Probability Sampling of Materials
upper and lower bounds represent the limits of an acceptable
E 122 Practice for Calculating Sample Size to Estimate,
bias.
with a Specified Tolerable Error, the Average for a Char-
3
3.2.8 mechanical sampling system, n—a single machine or
acteristic of a Lot or Process
3
series of interconnected machines whose purpose is to extract
E 456 Terminology Relating to Quality and Statistics
mechanically, or process (divide and reduce), or a combination
E 691 Practice for Conducting an Interlaboratory Study to
3
thereof, a sample of coal.
Determine the Precision of a Test Method
3.2.9 paired data set, n—system and reference values ob-
3. Terminology
served on samples collected and compared from the same batch
of material.
3.1 Definitions—For additional definitions of terms used in
3.2.10 reference sample, n—a sample used in testing of a
this practice refer to Terminologies D 121 and E 456.
mechanical sampling system which is comprised of one or
more increments collected from the test batch or lot of coal by
1
This practice is under the jurisdiction of ASTM Committee D05 on Coal and
the stopped belt method as described in Practice D 2234.
Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.
3.2.11 reject stream, n—the coal flow within a mechanical
Current edition approved June 10, 2002. Published August 2003.
Originally approved in 2000. Last previous edition approved in 2002 as D
sampling system, which occurs at each stage of division, before
6518–02a.
and after reduction, and is not included in the system sample.
2
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