Contents

Copyright

Preliminary

Foreword

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 uncertainty

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

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 uncertainty

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 evaluation of standard uncertainty

F.2   Components evaluated by other means: Type B evaluation of standard uncertainty

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.2   Simultaneous resistance and reactance measurement

H.3   Calibration of a thermometer

H.4   Measurement of activity

H.5   Analysis of variance

H.6   Measurements on a reference scale: hardness

Annex J — Glossary of principal symbols

Bibliography

Alphabetical index