DIN ISO 13528:2025-07

This document provides detailed descriptions of statistical methods for proficiency testing providers to use to design proficiency testing schemes and to analyse the data obtained from those schemes. This document provides recommendations on the interpretation of proficiency testing data by participants in such proficiency testing schemes and by accreditation bodies. The procedures in this document can be applied to demonstrate that the measurement results obtained by laboratories, inspection bodies, and individuals meet specified criteria for acceptable performance. This document is applicable to proficiency testing where the results reported are either quantitative measurements or qualitative observations on test items. Compared to DIN ISO 13528:2020-09, the title has been changed, the translation of some terms has been adapted to those used in DIN EN ISO/IEC 17043, and notes have been added to 10.1, 10.4.3 and 10.5.3 to draw attention to additional graphical techniques that can assist in meeting the provisions of 10.1; Annex B is now informative; formula (B.5) and formula (B.8) have been corrected, formula (B.16) has been corrected so that the term inside the square root is always non-negative; in Table C.2, the correction factor associated with p = 2 has been corrected to read 0,399 4; - additional literature references to the source of values in Table C.2 have been added to the Bibliography and referenced from Notes 1 and 2 of C.5.2.1; - font styles (italic or non-italic) have been amended throughout for consistency in formulae. This document (ISO 13528:2022) has been prepared by Technical Committee ISO/TC 69 "Applications of statistical methods", the secretariat of which is held by ANSI (USA). The responsible German committee is Working Group NA 119-01-03-06-04 AK "Ringversuche zur Eignungsprüfung" "Interlaboratory tests for proficiency testing" of Working Committee NA 119-01-03 AA "Water examination" at DIN Standards Committee Water Practice (NAW). The German co-sponsor is DIN Standards Committee Quality Management, Statistics and Certification (NQSZ).