TS ISO 13528

TS ISO 13528 addresses the statistical methods used in proficiency testing by interlaboratory comparison. It brings together the statistical tools used to design proficiency testing schemes and to evaluate the data generated from those schemes, while also supporting interpretation by participants and accreditation bodies.

The role of statistics in proficiency testing

Proficiency testing is used to review the performance of laboratories, inspection bodies, or individuals in a comparative way. In this context, the key questions are whether reported results meet acceptable performance criteria and how to assess them against a reference value, interlaboratory spread, or other suitable summary statistics. The focus of this standard is the statistical treatment that makes those evaluations consistent and defensible.

Data types covered and practical use

• Methods applicable to quantitative measurement results
• Nominal assessments suitable for qualitative observations and classifications
• Guidance for proficiency testing providers on scheme design and data analysis
• Recommendations for participants and accreditation bodies when interpreting results
• Situations where expert opinions or judgments can be compared objectively with a reference value or consensus statistic

In general technical terms, these methods help reduce the influence of outliers, summarize central tendency and variability robustly, compare performance on a common basis, and evaluate categorical outcomes. The standard’s core value is to provide a systematic statistical framework for a wide range of proficiency testing scenarios, from measurements to classification exercises.