ISO 13528:2022/Amd 1:2026

• Status: Published
• Publication Date: 27-Jul-2026
• ICS: 03.120.30 - Application of statistical methods
• Technical Committee: ISO/TC 69/SC 6 - Measurement methods and results
• Drafting Committee: ISO/TC 69/SC 6 - Measurement methods and results
• Current Stage: 6060 - International Standard published
• Start Date: 28-Jul-2026
• Due Date: 12-Jul-2026
• Completion Date: 28-Jul-2026

• Amends: ISO 13528:2022 - Statistical methods for use in proficiency testing by interlaboratory comparison
• Effective Date: 13-Jul-2024

ISO 13528:2022/Amd 1:2026 is Amendment 1 to ISO 13528:2022, the ISO document on statistical methods for use in proficiency testing by interlaboratory comparison. It updates cross-references, wording, formulas and one worked example used when evaluating proficiency testing (PT) data.

What does ISO 13528:2022/Amd 1:2026 specify?

ISO 13528:2022/Amd 1:2026 specifies targeted changes to the third edition of ISO 13528 for use in PT by interlaboratory comparison. The amendment is organized as replacement text in the foreword and introduction, clause-level edits in the main body, and corrections in Annex C and Annex E.

Annex	What it covers
Annex C	Statistical procedures and formulas used in the document, including corrected formula references and procedure wording
Annex E	A worked proficiency test example, including Table E.12 and its assigned value and scoring note

What are the key requirements of ISO 13528:2022/Amd 1:2026?

ISO 13528:2022/Amd 1:2026 mainly tightens the statistical and documentary rules around PT evaluation. For a user, the practical effect is that the revised references, assumptions, formulas and example data must be followed exactly when applying the standard.

• Foreword correction - the amendment corrects the listed formula references from B.4 and B.8 to B.5 and B.8. In practice, this matters when a reader follows the annex formulas and wants the right equation locations.

• Updated ISO/IEC 17043 references - the introduction and several clauses now point to ISO/IEC 17043 and ISO/IEC 17043:2023 instead of the earlier 2010 references. This keeps the PT method aligned with the current PT provider standard.

• Clause 3.4 wording - the note to the definition now states that the standard deviation for proficiency assessment can be interpreted in a specific way, and the source is updated to ISO/IEC 17043:2023. This matters because the standard is clarifying how the PT spread parameter should be understood.

• Clause 5.3.5 documentation of assumptions - the PT provider must document the reasons for statistical assumptions and show that they are reasonable. In practice, this means the chosen model is not just applied by habit - it must be justified in the PT record.

• Clause 6.3.1 handling of unsuitable results - the amendment points to documented criteria and procedures for results that are not suitable for statistical evaluation, and it cites early removal of obvious blunders before robust procedures or outlier tests. This matters because bad data must be screened before it affects scoring.

• Clause 7.7.7 method choice - the amendment extends the allowed procedures to those in C.2, C.3 or C.5. For users, this widens the documented method options while keeping them tied to Annex C.

• Annex C formula corrections - Formulae (C.18) and (C.19) are corrected, and the wording around MADe in C.3.2 b) is amended. If you implement the calculations in software or spreadsheets, these corrected expressions are the ones to use.

• Annex E example update - Table E.12 changes the assigned value for round code 104, proficiency test item C, and adds a note on rounding. This affects the worked example and any training or checking based on that table.

What terms does ISO 13528:2022/Amd 1:2026 define?

ISO 13528:2022/Amd 1:2026 uses a small set of terms that matter for PT work and data review.

• Proficiency testing (PT) - a comparison scheme used to assess how participants perform against a common basis for comparison.
• PT provider - the organization that runs the proficiency testing scheme and must justify the statistical choices used in evaluation.
• Standard deviation for proficiency assessment - the spread parameter used to judge participant performance in PT scoring.
• Statistical assumptions - the underlying assumptions behind a statistical analysis that must be documented and shown to be reasonable.
• Results inappropriate for statistical evaluation - measurement or test results that need to be excluded or handled by defined criteria before analysis.
• Obvious blunders - clear data errors that should be removed early, before robust statistics or outlier tests are applied.
• MADe - a named procedure in Annex C that the amendment now allows in one of the cited procedure sets.

Who uses ISO 13528:2022/Amd 1:2026?

ISO 13528:2022/Amd 1:2026 is used by PT providers, laboratory quality managers, statisticians, and people who design or review interlaboratory comparison schemes. It is also relevant to laboratories taking part in PT, because it affects how their results are evaluated, screened and scored. Accreditation and assessment teams use it to check whether the statistical treatment of PT data is documented and consistent.

What changed in ISO 13528:2022/Amd 1:2026 from the previous edition?

ISO 13528:2022/Amd 1:2026 amends ISO 13528:2022. The amendment corrects formula references, updates ISO/IEC 17043 references to the 2023 edition, revises wording in clause 3.4, adds clearer requirements for documenting statistical assumptions, strengthens the treatment of unsuitable results, extends the Annex C procedure reference, and revises the Annex E example table.

Which standards are used with ISO 13528:2022/Amd 1:2026?

ISO 13528:2022/Amd 1:2026 refers to ISO/IEC 17043:2023 throughout the amended text. That standard provides the current PT provider requirements that the amendment aligns with, including the clauses cited in 5.2.1, 5.3.5, 5.4.1, 5.5.1.1, 6.3.1, 9.2.1 and 9.4.2.

The amendment also cites ISO/IEC 17043 in the introduction and the IUPAC Harmonized Protocol in clause 6.3.1. ISO/IEC Directives, Part 1 and Part 2 are named in the foreword as the documents that govern ISO drafting and maintenance, so they explain how the standard was prepared.

What does the ISO 13528:2022/Amd 1:2026 document contain?

ISO 13528:2022/Amd 1:2026 contains replacement text for the foreword, introduction and several clauses, plus formula corrections in Annex C and a revised worked example in Annex E. It gives users the exact wording to insert into ISO 13528:2022 where cross-references, definitions or statistical procedures have been updated. Annex C supports calculation work, while Annex E supports checking and training with example PT scoring data.

International
Standard
ISO 13528
Third edition
Statistical methods for use
2022-08
in proficiency testing by
interlaboratory comparison
AMENDMENT 1
2026-07
AMENDMENT 1
Méthodes statistiques utilisées dans les essais d'aptitude par
comparaison interlaboratoires
AMENDEMENT 1
Reference number
ISO 13528:2022/Amd.1:2026(en) © ISO 2026

ISO 13528:2022/Amd.1:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii
ISO 13528:2022/Amd.1:2026(en)
Foreword
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Norme
internationale
ISO 13528
Troisième édition
Méthodes statistiques utilisées
2022-08
dans les essais d'aptitude par
comparaison interlaboratoires
AMENDEMENT 1
2026-07
AMENDEMENT 1
Statistical methods for use in proficiency testing by
interlaboratory comparison
AMENDMENT 1
Numéro de référence
ISO 13528:2022/Amd.1:2026(fr) © ISO 2026

ISO 13528:2022/Amd.1:2026(fr)
DOCUMENT PROTÉGÉ PAR COPYRIGHT
© ISO 2026
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Publié en Suisse
ii
ISO 13528:2022/Amd.1:2026(fr)
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