ASTM D6518-01

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-Apr-2001
• ICS: 73.040 - Coals
• Technical Committee: D05 - Coal and Coke
• Drafting Committee: D05.23 - Sampling

Relations

• Replaced By: ASTM D6518-02 - Standard Practice for Bias Testing a Mechanical Coal Sampling System
• Effective Date: 10-Jun-2002

Standards Content (Sample)

Designation: D 6518 – 01
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 of the mechanical sampler test results and the accepted
reference value.
1.1 This practice presents sample collection and statistical
3.2.2 confidence interval, n—a numeric interval with a
evaluation procedures for testing mechanical sampling sys-
lower limit and a higher limit within which the true parameter
tems, subsystems, and individual system components for bias.
value is estimated to fall. The confidence interval percentage
It is the responsibility of the user of this practice to select the
indicates the percentage of time the true value will fall within
appropriate procedure for a specific sampling situation.
the interval if the procedure is continuously repeated.
1.2 This practice does not purport to define an absolute bias.
3.2.3 correlation, n—a measure of the linear dependence
Bias defined by this practice is the difference between the
between paired system and reference measurements. Correla-
population mean of the mechanical sampler test results and the
tion frequently is expressed by the correlation coefficient,
accepted reference value.
which can take a value from minus one (perfect negative linear
1.3 This standard does not purport to address all of the
relationship) to plus one (perfect positive linear relationship).
safety concerns, if any, associated with its use. It is the
3.2.4 delimitation error, n—a material error that occurs
responsibility of the user of this standard to establish appro-
when all the elements in a cross section of a coal stream do not
priate safety and health practices and determine the applica-
have an equal probability of being intercepted (captured) by the
bility of regulatory limitations prior to use.
sampler cutter during increment collection.
2. Referenced Documents 3.2.5 ellipsoidal region, n—an area that is formed by plane
sections of ellipses that are defined by the values selected for
2.1 ASTM Standards:
2
the largest tolerable bias of each coal characteristic used in the
D 121 Terminology of Coal and Coke
2
bias test. The region will be used to determine if the system is
D 2013 Method of Preparing Coal Samples for Analysis
2
biased.
D 2234 Practice for Collection of a Gross Sample of Coal
2
3.2.6 Hotelling’s T test, n—a statistical test that is used to
D 4621 Guide for Accountability and Quality Control in the
2
evaluate multivariate data. It is the multivariate equivalent of
Coal Analysis Laboratory
the Student’s t-test.
D 4702 Guide for Inspecting Crosscut, Sweep-Arm, and
3.2.7 largest tolerable bias (LTB), n—an interval whose
Auger Mechanical Coal Sampling Systems for Conform-
2
upper and lower bounds represent the limits of an acceptable
ance with Current ASTM Standards
3
bias.
E 105 Practice for Probability Sampling of Materials
3.2.8 mechanical sampling system, n—a single machine or
E 122 Practice for Choice of Sample Size to Estimate a
3
series of interconnected machines whose purpose is to extract
Measure of Quality for a Lot or Process
3
mechanically, or process (divide and reduce), or a combination
E 456 Terminology Relating to Quality and Statistics
thereof, a sample of coal.
E 691 Practice for Conducting an Interlaboratory Study to
3
3.2.9 paired data set, n—system and reference values ob-
Determine the Precision of a Test Method
served on samples collected and compared from the same batch
3. Terminology
of material.
3.2.10 reference sample, n—a sample used in testing of a
3.1 Definitions—For additional definitions of terms used in
mechanical sampling system which is comprised of one or
this practice refer to Terminologies D 121 and E 456.
more increments collected from the test batch or lot of coal by
3.2 Definitions of Terms Specific to This Standard:
the stopped belt method as described in Practice D 2234.
3.2.1 bias, n—the difference between the population mean
3.2.11 reject stream, n—the coal flow within a mechanical
sampling system, which occurs at each stage of division, before
1
This practice is under the jurisdiction of ASTM Committee D05 on Coal and
and after reduction, and is not included in the system sample.
Coke and is the direct responsibility of Subcommittee D05.23 on Sampling.
Current edition approved April 10, 2001. Published June 2001. 3.2.12 save stream, n—the coal flow within a mechanical
Originally published as D 6518–00. Last previous edition D 6518–00.
sampling system which occurs at each stage of division, before
2
Annual Book of ASTM Standards, Vol 05.06.
and after reduction, and after the final stage of division
3
Annual Book of ASTM Standards, Vol 14.02.
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