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ISO/IEC GUIDE 98-3-2008 uncertainty of measurement -- part 3: guide to the expression of uncertainty in measurement (gum:1995)

Standard Number:  ISO/IEC GUIDE 98-3-2008
Title:  uncertainty of measurement -- part 3: guide to the expression of uncertainty in measurement (gum:1995)
Language:  English
Publication Date:  2008/9/30
Execute Date:  2008/9/30
Adopted International Standard:  [db:AdoptedInternationalStandardNo]
Status:  Current
CCS Classification for Standardscomprehensive>>measurement>>Measuring the comprehensive
Publisher:  International Organization for Standardization (ISO)
Number of Pages:130  

Description:1.1 This Guide establishes general rules for evaluating and expressing uncertainty in measurement that can be followed at various levels of accuracy and in many fields — from the shop floor to fundamental research. Therefore, the principles of this Guide are intended to be applicable to a broad spectrum of measurements, including those required for: -maintaining quality control and quality assurance in production; -complying with and enforcing laws and regulations; -conducting basic research, and applied research and development, in science and engineering; -calibrating standards and instruments and performing tests throughout a national measurement system in order to achieve traceability to national standards; -developing, maintaining, and comparing international and national physical reference standards, including reference materials. 1.2 This Guide is primarily concerned with the expression of uncertainty in the measurement of a well-defined physical quantity — the measurand — that can be characterized by an essentially unique value. If the phenomenon of interest can be represented only as a distribution of values or is dependent on one or more parameters, such as time, then the measurands required for its description are the set of quantities describing that distribution or that dependence. 1.3 This Guide is also applicable to evaluating and expressing the uncertainty associated with the conceptual design and theoretical analysis of experiments, methods of measurement, and complex components and systems. Because a measurement result and its uncertainty may be conceptual and based entirely on hypothetical data, the term “result of a measurement” as used in this Guide should be interpreted in this broader context. 1.4 This Guide provides general rules for evaluating and expressing uncertainty in measurement rather than detailed, technology-specific instructions. Further, it does not discuss how the uncertainty of a particular measurement result, once evaluated, may be used for different purposes, for example, to draw conclusions about the compatibility of that result with other similar results, to establish tolerance limits in a manufacturing process, or to decide if a certain course of action may be safely undertaken. It may therefore be necessary to develop particular standards based on this Guide that deal with the problems peculiar to specific fields of measurement or with the various uses of quantitative expressions of uncertainty.* These standards may be simplified versions of this Guide but should include the detail that is appropriate to the level of accuracy and complexity of the measurements and uses addressed.  
Cross References:[db:refbz]  
Catalog:Document Contents<" style="border-width:0;" />Document Contents
Guide 98-3 - Uncertainty of measurement - Part 3: Guide to the expression of uncertainty...
0 Introduction
1 Scope
2 Definitions
2.1 General metrological terms
2.2 The term ?uncertainty?
2.3 Terms specific to this Guide
3 Basic concepts
3.1 Measurement
3.2 Errors, effects, and corrections
3.3 Uncertainty
3.4 Practical considerations
4 Evaluating standard uncertainty
4.1 Modelling the measurement
4.2 Type A evaluation of standard uncertainty
4.3 Type B evaluation of standard uncertainty
4.4 Graphical illustration of evaluating standard uncertainty
5 Determining combined standard uncertainty
5.1 Uncorrelated input quantities
5.2 Correlated input quantities
6 Determining expanded uncertainty
6.1 Introduction
6.2 Expanded uncertainty
6.3 Choosing a coverage factor
7 Reporting uncertainty
7.1 General guidance
7.2 Specific guidance
8 Summary of procedure for evaluating and expressing uncertain
Annex A - Recommendations of Working Group and CIPM
A.1 Recommendation INC-1 (1980)
A.2 Recommendation 1 (CI-1981)
A.3 Recommendation 1 (CI-1986)
Annex B - General metrological terms
B.1 Source of definitions
B.2 Definitions
Annex C - Basic statistical terms and concepts
C.1 Source of definitions
C.2 Definitions
C.3 Elaboration of terms and concepts
C.3.1 Expectation
C.3.2 Variance
C.3.3 Standard deviation
C.3.4 Covariance
C.3.5 Covariance matrix
C.3.6 Correlation coefficient
C.3.7 Independence
C.3.8 The t-distribution; Student's distribution
Annex D - "True" value, error, and uncertainty
D.1 The measurand
D.2 The realized quantity
D.3 The "true" value and the corrected value
D.4 Error
D.5 Uncertainty
D.6 Graphical representation
Annex E - Motivation and basis for Recommendation INC-1 (1980)
E.1 "Safe", "random", and "systematic"
E.2 Justification for realistic uncertainty evaluations
E.3 Justification for treating all uncertainty components identically
E.4 Standard deviations as measures of uncertainy
E.5 A comparison of two views of uncertainty
Annex F - Practical guidance on evaluating uncertainty components
F.1 Components evaluated from repeated observations: Type A
F.1.1 Randomness and repeated observations
F.1.2 Correlations
F.2 Components evaluated from repeated observations: Type B
F.2.1 The need for Type B evaluations
F.2.2 Mathematically determinate distributions
F.2.3 Imported input values
F.2.4 Measured input values
F.2.5 Uncertainty of the method of measurement
F.2.6 Uncertainty of the sample
Annex G - Degrees of freedom and levels of confidence
G.1 Introduction
G.2 Central Limit Theorem
G.3 The t-distribution and degrees of freedom
G.4 Effective degrees of freedom
G.5 Other considerations
G.6 Summary and conclusions
Annex H - Examples
H.1 End-gauge calibration
H.1.1 The measurement problem
H.1.2 Mathematical model
H.1.3 Contributory variances
H.1.4 Combined standard uncertainty
H.1.5 Final result
H.1.6 Expanded uncertainty
H.1.7 Second-order terms
H.2 Simultaneous resistance and reactance measurement
H.2.1 The measurement problem
H.2.2 Mathematical model and data
H.2.3 Results: approach 1
H.2.4 Results: approach 2
H.3 Calibration of a thermometer
H.3.1 The measurement problem
H.3.2 Least-squares fitting
H.3.3 Calculation of results
H.3.4 Uncertainty of a predicted value
H.3.5 Elimination of the correlation between the slope and intercept
H.3.6 Other considerations
H.4 Measurement of activity
H.4.1 The measurement problem
H.4.2 Analysis of data
H.4.3 Calculation of final results
H.5 Analysis of variance
H.5.1 The measurement problem
H.5.2 A numerical example
H.5.3 The role of ANOVA in measurement
H.6 Measurements on a reference scale: hardness
H.6.1 The measurement problem
H.6.2 Mathematical model
H.6.3 Contributory variances
H.6.4 The combined standard uncertainty
H.6.5 Numerical example
Annex J - Glossary of principal symbols
Alphabetical index
File Format:  PDF(Acrobat Reader) or Word version doc Document
File Size:  724KB
Tile in English:  uncertainty of measurement -- part 3: guide to the expression of uncertainty in measurement (gum:1995)

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