ASTM E691-08

1.1 This practice describes the techniques for planning, conducting, analyzing, and treating the results of an interlaboratory study (ILS) of a test method. The statistical techniques described in this practice provide adequate information for formulating the precision statement of a test method.

1.2 This practice does not concern itself with the development of test methods but rather with gathering the information needed for a test method precision statement after the development stage has been successfully completed. The data obtained in the interlaboratory study may indicate, however, that further effort is needed to improve the test method.

1.3 Since the primary purpose of this practice is the development of the information needed for a precision statement, the experimental design in this practice may not be optimum for evaluating materials, apparatus, or individual laboratories.

1.4 Field of Application – This practice is concerned exclusively with test methods which yield a single numerical figure as the test result, although the single figure may be the outcome of a calculation from a set of measurements.

1.4.1 This practice does not cover methods in which the measurement is a categorization, such as a go-no-go allocation (two categories) or a sorting scheme into two or more categories. For practical purposes, the discontinuous nature of measurements of these types may be ignored when a test result is defined as an average of several individual measurements. Then, this practice may be applicable, but caution is required and a statistician should be consulted.

1.5 The information in this practice is arranged as follows:

	Section
Scope	1
Referenced Documents	2
Terminology	3
Summary of Practice	4
Significance and Use	5
Planning the Interlaboratory Study (ILS)
ILS Membership	6
Basic Design	7
Test Method	8
Laboratories	9
	Section
Materials	10
Number of Test Results per Material	11
Protocol	12
Conducting the Testing Phase of the ILS
Pilot Run	13
Full Scale Run	14
	Section
Calculation and Display of Statistics
Calculation of the Statistics	15
Tabular and Graphical Display of Statistics	16
Data Consistency
Flagging Inconsistent Results	17
Investigation	18
Task Group Actions	19
Examples of Interlaboratory Studies	20
Precision Statement Information
Repeatability and Reproducibility	21
Appendixes
Theoretical Considerations	A1
Index to Selected Terms	A2
References
Tables and Figures
Tables	Table
Glucose in Serum Example	1–4 & 6–7
Pentosans in Pulp Example	8–11
Critical Values of Consistency Statistics, h and k	5
Figures	Fig.
Glucose in Serum Example	1–5
Pentosans in Pulp Example	6–10

1.6 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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.

Product Details

Published:

10/01/2008

Number of Pages:

23

File Size:

1 file , 260 KB

Redline File Size:

2 files , 460 KB

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