ISO 4259-3:2020 PDF

Petroleum and related products — Precision of measurement methods and results — Part 3: Monitoring and verification of published precision data in relation to methods of test

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Title (English):

ISO 4259-3:2020

Petroleum and related products — Precision of measurement methods and results — Part 3: Monitoring and verification of published precision data in relation to methods of test

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 14
Publication date:: January 16, 2020
Edition:: ISO IS 4259 edition 1 version 1
ICS:: 75.080

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Description (English):

This document specifies the methodology for the regular monitoring of the test method precision achieved versus the precision published in the standard test method using data from proficiency testing schemes (PTSs) supported by the regular users of standard test methods. The procedures in this document are designed specifically for proficiency testing (PT) conducted on standard test methods, having a published reproducibility, for petroleum and petroleum-related products, which are presumed to be homogeneous, and where the data distribution is approximately normal. In addition, it is applicable to properties of interest that are (known to be) stable over time and transport. This document specifies the methodology for the statistical comparison of standard deviation under reproducibility conditions achieved in PT programmes versus that published. The purpose of this comparison is to find out if the published reproducibility precision is representative of that achievable by the regular participants in the PT programmes. This document also provides guidance on how to use a PT z-score to monitor an individual participant's performance over time (see Annex B).

Technical details

Technical committee: ISO/TC 28 - Petroleum and related products, fuels and lubricants from natural or synthetic sources
SKU: ISO 4259-3:2020

Abstract

Overview

ISO 4259-3:2020 - "Petroleum and related products - Precision of measurement methods and results - Part 3" defines a statistical methodology for regularly monitoring whether the precision (reproducibility) published in a standard test method remains representative of results achieved in practice. The standard uses data from proficiency testing schemes (PTS) and interlaboratory comparisons to compare the reproducibility achieved in PT rounds against the published reproducibility in the test method.

Key technical topics and requirements

Scope: Applies to petroleum and related products that are presumed homogeneous and whose properties are stable over time and transport; data distribution should be approximately normal.
Data prerequisites:
- Results must be numeric and derived using a common standard test method with a published reproducibility (from ISO 4259-1 or equivalent).
- Single result per participant per round (no repeats).
- PT statistics should be based on at least 10 results (16 recommended) with at least 6 uniquely different values after outlier rejection.
Statistical checks and preprocessing:
- Outlier detection using GESD (generalized extreme studentized deviation) consistent with ISO 4259-1.
- Normality assessed (e.g., Anderson–Darling or Shapiro–Wilk) at the 0.01 significance level.
- PT standard deviation calculated using the root-mean-square method.
Main test: Compare the PT round reproducibility (S_R_PT) to the published reproducibility (S_R_pub) by forming a variance ratio and performing an F‑test.
- Published reproducibility may be adjusted by a k‑value (table provided) or, if degrees of freedom (df) are unknown, divide by 2.888 (default based on df = 30).
- The larger variance is placed in the numerator; use the upper 97.5 percentile of the F-distribution as the critical value for a 5% two‑sided test.
- If the variance ratio exceeds the critical F, the published reproducibility is considered inconsistent with the PT results for that round.
Monitoring individuals: Annex B provides guidance on using z‑scores from PT rounds to track individual laboratory performance over time.

Practical applications and who uses it

PT scheme providers: design reports and statistical evaluations aligned with ISO 4259-3 requirements.
Testing laboratories and QA managers: verify that published method precision matches routine performance; monitor long‑term performance using z‑scores.
Standards committees and method authors: validate and update published reproducibility values using field PT data.
Accreditation bodies and regulators: assess ongoing method performance and conformity in interlaboratory programs.
Industry quality teams (refining, fuels, lubricants): ensure measurement consistency across suppliers and service labs.

Related standards

ISO 4259-1 - Determination of precision data in relation to methods of test
ISO 13528:2015 - Statistical methods for proficiency testing by interlaboratory comparison
ISO/IEC 17043 - General requirements for proficiency testing providers

Keywords: ISO 4259-3:2020, precision of measurement methods, proficiency testing schemes, F-test variance ratio, published reproducibility, petroleum testing, z-score monitoring, interlaboratory comparisons.

Related standards

Standards mentioned in the description

Abstract

Overview

Key technical topics and requirements

Scope: Applies to petroleum and related products that are presumed homogeneous and whose properties are stable over time and transport; data distribution should be approximately normal.
Data prerequisites:
- Results must be numeric and derived using a common standard test method with a published reproducibility (from ISO 4259-1 or equivalent).
- Single result per participant per round (no repeats).
- PT statistics should be based on at least 10 results (16 recommended) with at least 6 uniquely different values after outlier rejection.
Statistical checks and preprocessing:
- Outlier detection using GESD (generalized extreme studentized deviation) consistent with ISO 4259-1.
- Normality assessed (e.g., Anderson–Darling or Shapiro–Wilk) at the 0.01 significance level.
- PT standard deviation calculated using the root-mean-square method.
Main test: Compare the PT round reproducibility (S_R_PT) to the published reproducibility (S_R_pub) by forming a variance ratio and performing an F‑test.
- Published reproducibility may be adjusted by a k‑value (table provided) or, if degrees of freedom (df) are unknown, divide by 2.888 (default based on df = 30).
- The larger variance is placed in the numerator; use the upper 97.5 percentile of the F-distribution as the critical value for a 5% two‑sided test.
- If the variance ratio exceeds the critical F, the published reproducibility is considered inconsistent with the PT results for that round.
Monitoring individuals: Annex B provides guidance on using z‑scores from PT rounds to track individual laboratory performance over time.

Practical applications and who uses it

PT scheme providers: design reports and statistical evaluations aligned with ISO 4259-3 requirements.
Testing laboratories and QA managers: verify that published method precision matches routine performance; monitor long‑term performance using z‑scores.
Standards committees and method authors: validate and update published reproducibility values using field PT data.
Accreditation bodies and regulators: assess ongoing method performance and conformity in interlaboratory programs.
Industry quality teams (refining, fuels, lubricants): ensure measurement consistency across suppliers and service labs.

Related standards

ISO 4259-1 - Determination of precision data in relation to methods of test
ISO 13528:2015 - Statistical methods for proficiency testing by interlaboratory comparison
ISO/IEC 17043 - General requirements for proficiency testing providers

ISO 4259-3:2020 PDF

Technical details

Abstract

Overview

Key technical topics and requirements

Practical applications and who uses it

Related standards

Related standards

Abstract

Overview

Key technical topics and requirements

Practical applications and who uses it

Related standards

Related standards

Statistical methods for use in proficiency testing by interlaboratory comparison

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