ASTM C1215-18

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´1
Designation: C1215 − 92 (Reapproved 2012) C1215 − 18
Standard Guide for
Preparing and Interpreting Precision and Bias Statements in
1
Test Method Standards Used in the Nuclear Industry
This standard is issued under the fixed designation C1215; 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 (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—Changes were made editorially in June 2012.
INTRODUCTION
Test method standards are required to contain precision and bias statements. This guide contains a
glossary that explains various terms that often appear in these statements as well as an example
illustrating such statements for a specific set of data. Precision and bias statements are shown to vary
according to the conditions under which the data were collected. This guide emphasizes that the error
model (an algebraic expression that describes how the various sources of variation affect the
measurement) is an important consideration in the formation of precision and bias statements.
1. Scope
1.1 This guide covers terminology useful for the preparation and interpretation of precision and bias statements. This guide does
not recommend a specific error model or statistical method. It provides awareness of terminology and approaches and options to
use for precision and bias statements.
1.2 In formulating precision and bias statements, it is important to understand the statistical concepts involved and to identify
the major sources of variation that affect results. Appendix X1 provides a brief summary of these concepts.
1.3 To illustrate the statistical concepts and to demonstrate some sources of variation, a hypothetical data set has been analyzed
in Appendix X2. Reference to this example is made throughout this guide.
1.4 It is difficult and at times impossible to ship nuclear materials for interlaboratory testing. Thus, precision statements for test
methods relating to nuclear materials will ordinarily reflect only within-laboratory variation.
1.5 No units are used in this statistical analysis.
1.6 This guide does not involve the use of materials, operations, or equipment and does not address any risk associated.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
C859 Terminology Relating to Nuclear Materials
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 ANSI Standard:
3
ANSI N15.5 Statistical Terminology and Notation for Nuclear Materials Management
1
This guide is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.08 on Quality Assurance,
Statistical Applications, and Reference Materials.
Current edition approved June 1, 2012July 1, 2018. Published June 2012July 2018. Originally approved in 1992. Last previous edition approved in 20062012 as
ɛ1
C1215–92(2006).C1215 – 92 (2012) . DOI: 10.1520/C1215-92R12E01.10.1520/C1215-18.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
C1215 − 18
3. Terminology for Precision and Bias Statements
3.1 For definitions of terms used in this guide but not defined herein, see Terminology C859.
3.2 Definitions:Terminology for Precision and Bias Statements
3.2.1 accuracy (seebias) —(1) bias. (2) the closeness of a measured value to the true value. (3) the closeness of a measured value
to an accepted reference or standard value.
3.2.1.1 Discussion—
For many investigators, accuracy is attained only if a procedure is both precise and unbiased (see bias). Because this blending of
precision into accuracy can result occasionally in incorrect analyses and unclear statements of resu
...