ASTM E177-90a(2002)
Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods

Standard No.

ASTM E177-90a(2002)

Release Date

1990

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM E177-04

Latest

ASTM E177-20

Scope

1.1 The purpose of this practice is to present concepts necessary to the understanding of the terms "precision" and "bias" as used in quantitative test methods. This practice also describes methods of expressing precision and bias and, in a final section, gives examples of how statements on precision and bias may be written for ASTM test methods. The term "accuracy", used in earlier editions of Practice E 177, embraces both precision and bias (see Section 20 and Note 4).

1.2 Informal descriptions of the concepts are introduced in the text as the concepts are developed, and appear in the following sections:

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	Section
Terminology	3
Significance and Use	4
GENERAL CONCEPTS
Test Method	5
Measurement Terminology	6
Observation	7
Test Determination	8
Test Result	9
SOURCES OF VARIABILITY
Experimental Realization of a Test Method	10
Operator	11
Apparatus	12
Environment	13
Sample	14
Time	15
STATISTICAL CONCEPTS
Accepted Reference Value	16
Statistical Control	17
Precision	18
Bias	19
Accuracy	20
Variation of Precision and Bias with Material	21
Variation of Precision and Bias with Sources of Variability	22
COMBINATIONS OF SOURCES OF VARIABILITY
Repeatability and Laboratory Bias	23
Other Within-a-Single Laboratory Precisions	24
Reproducibility and Bias of the Test Method	25
Range of Materials	26
METHODS OF EXPRESSING PRECISION AND BIAS
Indexes of Precision	27
Preferred Indexes of Precision for ASTM Test Methods	28
Preferred Statements of Bias for ASTM Test Methods	29
Elements of a Statement of Precision and Bias	30
STATEMENTS OF PRECISION AND BIAS
Examples of Statements of Precision and Bias	31
APPENDIX
Alphabetical List of Descriptions of Terms from the Text	X1

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.

ASTM E177-90a(2002) history

• 2020 ASTM E177-20 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2019 ASTM E177-19 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2014 ASTM E177-14 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2013 ASTM E177-13 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2010 ASTM E177-10 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2008 ASTM E177-08 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2006 ASTM E177-06b Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2006 ASTM E177-06a Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2006 ASTM E177-06 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2004 ASTM E177-04e1 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 2004 ASTM E177-04 Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 1990 ASTM E177-90a(2002) Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• 1996 ASTM E177-90a(1996) Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods