ISO 21748-2017 PDF

Full title and description

ISO 21748:2017 — Guidance for the use of repeatability, reproducibility and trueness estimates in measurement uncertainty evaluation. Provides practical guidance on using data from interlaboratory and method‑performance studies to evaluate and express measurement uncertainty for test and measurement results.

Abstract

ISO 21748:2017 gives guidance for the evaluation of measurement uncertainties where information from studies conducted in accordance with the ISO 5725 series (interlaboratory/collaborative studies and intermediate precision studies) is used. It explains how repeatability, reproducibility and trueness estimates can be incorporated into uncertainty budgets, how to assess relevance of method performance data to particular measurement processes and test items, and how to compare collaborative study results with uncertainty estimates derived by formal propagation methods. The document is intended as practical guidance and does not replace either the ISO 5725 series or the general principles of uncertainty evaluation (GUM/JCGM guidance).

General information

• Status: Published (International Standard, current edition).
• Publication date: 24 April 2017 (Edition 2, 2017).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 17.020 — Metrology and measurement in general.
• Edition / version: Edition 2 (2017).
• Number of pages: 38 pages (ISO edition).

Scope

Applies to all measurement and testing fields where an uncertainty associated with a result must be determined and where method performance data (repeatability, reproducibility, trueness) are available from collaborative or other suitable studies. The standard covers use of such performance estimates in uncertainty evaluation and comparison of collaborative study results with uncertainties obtained by formal uncertainty propagation. It does not address use of repeatability data alone in the absence of reproducibility information, and it assumes known, non‑negligible systematic effects have been corrected or otherwise addressed.

Key topics and requirements

• Principles for incorporating repeatability, reproducibility and trueness estimates into uncertainty evaluation.
• Methods for evaluating uncertainty using data from ISO 5725‑2 style studies and related models.
• Establishing relevance of method performance data to specific measurement processes and to the test item under consideration.
• Consideration of additional factors (sample handling, environmental effects, operator influences) when applying study data.
• General expression and calculation of combined standard uncertainty including performance estimates.
• Construction of uncertainty budgets based on collaborative/interlaboratory data.
• Evaluation and reporting of uncertainty for combined results and multi‑source data.
• Guidance on expressing and communicating uncertainty information and limits of applicability of study data.

Typical use and users

Used by calibration and testing laboratories, quality managers, method developers, accreditation bodies, metrologists and statisticians. Typical applications include producing uncertainty budgets when method performance data exist, interpreting interlaboratory study results, demonstrating measurement capability to clients or accreditors, and comparing uncertainty estimates from collaborative studies with uncertainties obtained by propagation from individual influence factors.

Related standards

Closely related documents include the ISO 5725 series (accuracy of measurement methods and results — especially ISO 5725‑1, ‑2 and ‑3), the GUM/JCGM guidance for the expression of uncertainty in measurement (JCGM 100 / "GUM"), and laboratory accreditation requirements such as ISO/IEC 17025. It also relates to other ISO guidance and technical reports addressing statistical methods for interlaboratory studies and uncertainty evaluation.

Keywords

measurement uncertainty, repeatability, reproducibility, trueness, interlaboratory study, collaborative study, uncertainty budget, metrology, method performance, GUM, ISO 5725.

FAQ

Q: What is this standard?

A: ISO 21748:2017 is an ISO guidance document that explains how to use repeatability, reproducibility and trueness estimates from method‑performance and interlaboratory studies when evaluating and reporting measurement uncertainty.

Q: What does it cover?

A: It covers principles and practical approaches for incorporating performance estimates from collaborative/interlaboratory studies into uncertainty budgets, assessing the relevance of study data to a given measurement situation, and comparing such results with uncertainty values obtained by formal propagation methods.

Q: Who typically uses it?

A: Calibration and testing laboratories, method developers, accreditation bodies, metrologists and statisticians — essentially anyone who needs to use study‑derived performance data to justify or compute measurement uncertainty.

Q: Is it current or superseded?

A: The 2017 document is the second edition (published 24 April 2017) and replaced the earlier 2010 edition and preceding technical specification. It is the current ISO edition (published by ISO) unless a later review or revision has been issued after April 2017.

Q: Is it part of a series?

A: It is conceptually linked to the ISO 5725 series (which defines and specifies repeatability, reproducibility and interlaboratory test procedures) and to the GUM/JCGM uncertainty guidance; it is complementary to laboratory accreditation standards such as ISO/IEC 17025.

Q: What are the key keywords?

A: Measurement uncertainty, repeatability, reproducibility, trueness, interlaboratory, collaborative study, uncertainty budget, method performance.