ASTM-D4853 › Standard Guide for Reducing Test Variability (Withdrawn 2008)
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Scope
1.1 This guide serves as an aid to subcommittees writing and maintaining test methods. It helps to (1) determine if it is possible to reduce test variability, and, if so, ( 2) provide a systematic approach to the reduction.
1.2 This guide includes the following topics:
Topic Title | Section Number |
Scope | 1 |
Referenced Documents | 2 |
Definitions | 3 |
Significance and Use | 4 |
Measures of Test Variability | 5 |
Unnecessary Test Variability | 6 |
Identifying Probable Causes of Test Variability | 7 |
Determining the Causes of Test Variability | 8 |
Averaging | 9 |
Calibration | 10 |
Keywords | 11 |
1.3 The annexes include:
Topic Title | Annex Number |
Statistical Test Selection | Annex A1 |
Frequency Distribution Identification | Annex A2 |
Design of Ruggedness Tests | Annex A3 |
Ruggedness Test Analysis: | |
Unknown or Undefined Distribution—Small Sample | Annex A4 |
Unknown or Undefined Distribution—Large Sample | Annex A5 |
Binomial Distribution | Annex A6 |
Poisson Distribution | Annex A7 |
Normal Distribution | Annex A8 |
Design of a Randomized Block Experiment | Annex A9 |
Randomized Block Experiment Analysis: | |
Unknown or Undefined Distribution—Small Sample | Annex A10 |
Unknown or Undefined Distribution—Large Sample | Annex A11 |
Binomial Distribution | Annex A12 |
Poisson Distribution | Annex A13 |
Normal Distribution | Annex A14 |
Averaging: | |
No Compositing | Annex A15 |
Compositing | Annex A16 |
Significance and Use
This guide can be used at any point in the development or improvement of a test method, if it is desired to pursue reduction of its variability.
There are three circumstances in which a subcommittee responsible for a test method would want to reduce test variability:
4.2.1 During the development of a new test method, ruggedness testing might reveal factors which produce an unacceptable level of variability, but which can be satisfactorily controlled once the factors are identified.
4.2.2 Another is when analysis of data from an interlaboratory test of a test method shows significant differences between levels of factors or significant interactions which were not desired or expected. Such an occurrence is an indicator of lack of control which means that the precision of the test method is not predictable.
4.2.3 The third situation is when the method is in statistical control, but it is desired to improve its precision, perhaps because the precision is not good enough to detect practical differences with a reasonable number of specimens.
The techniques in this guide help to detect a statistical difference between test results. They do not directly answer questions about practical differences. A statistical difference is one which is not due to experimental error, that is, chance variation. Each statistical difference found by the use of this guide must be compared to a practical difference, the size of which is a matter of engineering judgment. For example, a change of one degree in temperature of water may show a statistically significant difference of 0.05 % in dimensional change, but 0.05 % may be of no importance in the use to which the test may be put.
Keywords
developing test methods; interlaboratory testing; ruggedness test design; statistics; uniformity; ICS Number Code 19.020 (Test conditions and procedures in general); 59.080.01 (Textiles in general)
To find similar documents by ASTM Volume:
07.02 (Textiles (II): D4393 - latest)
To find similar documents by classification:
19.020 (Test conditions and procedures in general)
59.080.01 (Textiles in general Including colour fastness of textiles)
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Document Number
ASTM-D4853-97(2002)
Revision Level
1997 R02 EDITION
Status
Cancelled
Modification Type
Withdrawn
Publication Date
Dec. 1, 2002
Document Type
Guide
Page Count
16 pages
Committee Number
D13.93