ASTM E2489-21 PDF

Overview

ASTM E2489-21: Standard Practice for Statistical Analysis of One-Sample and Two-Sample Interlaboratory Proficiency Testing Programs is a foundational document published by ASTM International for laboratories that participate in proficiency testing. This practice outlines robust, easy-to-apply statistical methods for analyzing data generated from interlaboratory proficiency testing, which is used to evaluate the performance of laboratories and the precision of test methods.

Proficiency testing, as defined in this standard, involves comparing test results from multiple laboratories to assess both individual and collective accuracy. ASTM E2489-21 provides guidelines for assessing laboratory performance and estimating both repeatability (within-laboratory) and reproducibility (between-laboratory) variations using one-sample and two-sample test designs. The approach assumes that all participant labs follow the same protocol and analyze homogeneous samples.

Key Topics

• One-Sample and Two-Sample Programs:
  • Method A: Each laboratory submits one result from a single sample.
  • Method B: Each laboratory submits results for two similar or essentially identical samples.
• Robust Statistical Methods:
  • Use of the median as a consensus value.
  • Application of interquartile range (IQR) to estimate data spread, enhancing resistance to the influence of outliers.
  • Categorization of laboratory results via Tukey inner and outer fences (using 1.5×IQR and 3×IQR thresholds).
• Evaluating Laboratory Performance:
  • Simple procedures to identify typical, unusual, and extremely unusual results.
  • Step-by-step approach for calculating and applying statistical measures to proficiency testing results.
• Estimating Repeatability and Reproducibility:
  • Methods for estimating within-laboratory and between-laboratory standard deviations from proficiency test data.
  • Clear requirements for minimum numbers of participating labs (typically ten or more).
• Visual Data Representation:
  • Use of tables, dot plots, and scatter diagrams to illustrate results and distribution patterns.

Applications

ASTM E2489-21 supports a broad range of scientific and industrial laboratory environments where interlaboratory proficiency testing is critical. Practical applications include:

• Quality Assurance Programs:
  • Regular assessment of laboratory testing performance for compliance, accreditation, and continuous improvement.
• Method Validation:
  • Determining if a testing method delivers consistent results across multiple labs to support decision-making on method adoption or improvement.
• Accreditation Bodies:
  • Evaluation of laboratory performance as part of accreditation or certification requirements.
• Standards Development:
  • Giving standards committees data-driven insights into actual test method performance under diverse conditions.

Testing program administrators, standards developers, and laboratory managers can use this practice to ensure their interlaboratory proficiency testing programs deliver statistically sound and actionable results.

Related Standards

ASTM E2489-21 references and complements several other important ASTM and international documents:

• ASTM E1301: Guide for Proficiency Testing by Interlaboratory Comparisons (historical reference)
• ASTM E691: Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• ASTM E177: Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• ASTM E178: Standard Practice for Dealing With Outlying Observations
• ASTM E456: Terminology Relating to Quality and Statistics
• ASTM E2586: Practice for Calculating and Using Basic Statistics

These related standards provide additional guidance on terminology, test method precision studies, and statistical analysis approaches for quality and bias evaluation.

Keywords: ASTM E2489-21, proficiency testing, interlaboratory comparison, statistical analysis, laboratory performance, repeatability, reproducibility, quality assurance, test method precision, Tukey fences, interquartile range, laboratory accreditation.