ISO IEC Guide 98-3-2008 PDF

Full title and description

ISO/IEC Guide 98-3:2008 — Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995). This publication is the 2008 reissue of the GUM (1995) with minor corrections and provides internationally accepted rules and procedures for evaluating and expressing uncertainty in measurement across scientific, industrial and regulatory applications.

Abstract

Provides general principles and practical procedures to evaluate and report measurement uncertainty. The Guide explains Type A and Type B evaluation of uncertainty, calculation of standard and combined uncertainties, and reporting of coverage intervals. It is intended for use across a wide range of measurement activities from routine calibration and quality control to research and fundamental metrology. The Guide is also linked to a set of supplements that extend or implement the computational phase (notably Monte Carlo propagation and multivariate output quantities).

General information

• Status: Published; confirmed current following periodic review.
• Publication date: 2008 (first published autumn 2008; corrected electronic version noted 2010).
• Publisher: International Organization for Standardization (ISO) in cooperation with IEC / JCGM (as applicable to the GUM family).
• ICS / categories: 17.020 (Metrology and measurement in general).
• Edition / version: Edition 1 (2008 reissue of the 1995 GUM, with minor corrections).
• Number of pages: Approximately 120 pages for the main Guide (supplements have separate page counts; Supplement 1 ≈ 88 pages, Supplement 2 ≈ 73 pages).

Scope

Establishes general rules for the evaluation and expression of uncertainty in measurement for a broad range of measurement problems. The Guide covers the construction of measurement models, assignment of probability distributions to input quantities (Type A and Type B evaluations), propagation of uncertainty through models to obtain an estimate of the measurand and its associated uncertainty, and presentation of coverage intervals. Supplements provide computational extensions (for example, propagation of distributions using a Monte Carlo method and extensions to multivariate output quantities).

Key topics and requirements

• Definition of the measurand and formulation of a measurement model.
• Type A (statistical) and Type B (other information) evaluation of standard uncertainties.
• Combination of standard uncertainties to obtain combined standard uncertainty and expanded uncertainty (coverage factors and coverage intervals).
• Guidance on reporting uncertainty and traceability of measurement results.
• Computational options and extensions: linear propagation (GUM approach) and numerical propagation using the Monte Carlo method (GUM Supplement 1 / JCGM 101).
• Multivariate output treatment and coverage regions (GUM Supplement 2).

Typical use and users

Used by national metrology institutes, calibration and testing laboratories, quality managers, regulatory bodies, instrument manufacturers, research laboratories and engineers who need to evaluate and report measurement uncertainty and maintain measurement traceability. The Guide is applied in calibration certificates, conformity assessment, research data reporting and standards development.

Related standards

Closely associated JCGM/ISO documents and supplements: JCGM 100 (GUM, JCGM 100:2008 / ISO/IEC Guide 98-3), JCGM 101 (GUM Supplement 1: Monte Carlo propagation), ISO/IEC Guide 98-3:2008/Suppl.1:2008 and ISO/IEC Guide 98-3:2008/Suppl.2:2011. Also related to VIM / JCGM 200 (International Vocabulary of Metrology) and other parts of the ISO/IEC Guide 98 series.

Keywords

measurement uncertainty; GUM; Guide to the expression of uncertainty in measurement; standard uncertainty; combined uncertainty; coverage interval; Monte Carlo; metrology; calibration; traceability.

FAQ

Q: What is this standard?

A: ISO/IEC Guide 98-3:2008 is the international Guide to the expression of uncertainty in measurement (GUM), reissued in 2008 with minor corrections; it sets out the principles and procedures for evaluating and reporting measurement uncertainty.

Q: What does it cover?

A: It covers measurement-model formulation, Type A and Type B evaluation of uncertainty, combination of uncertainties, and reporting of results (including expanded uncertainty and coverage intervals). Computational supplements (Monte Carlo and multivariate extensions) provide methods where the basic linear propagation assumptions are not appropriate.

Q: Who typically uses it?

A: Metrology institutes, calibration and testing laboratories, quality assurance and regulatory organisations, researchers and instrument manufacturers who need consistent, internationally accepted procedures for expressing measurement uncertainty.

Q: Is it current or superseded?

A: The 2008 reissue of the Guide was reviewed and confirmed in subsequent ISO reviews (the ISO entry notes a most recent review/confirmation in 2023), and supplements and corrigenda have been published to clarify or extend computational aspects. Users should check national adoption/publication records for the latest local status and any amendments or corrigenda.

Q: Is it part of a series?

A: Yes — it is part of the JCGM/ISO GUM family (JCGM 100 / ISO/IEC Guide 98-3 and its supplements JCGM 101 / ISO/IEC Guide 98-3 Supplement 1, Supplement 2, etc.), and ties into other JCGM guidance such as the VIM (JCGM 200).

Q: What are the key keywords?

A: Measurement uncertainty, GUM, standard uncertainty, combined uncertainty, coverage interval, Monte Carlo, metrology, calibration, traceability.