Investigating poor performance in proficiency testing
- Details
- Last Updated: Tuesday, 21 May 2024 20:24
Content
A laboratory will occasionally have a poor performance in a PT scheme. When this occurs, the laboratory should acknowledge it, carry out an investigation and document a review of possible causes, even if it decides not to take any specific action. This leaflet, prepared by the EURACHEM Proficiency Testing Working Group, gives advice for laboratories on how to best address such events.
This second edition is an editorial amendment to reference recent guidance on proficiency testing.
Availability
The second edition is currently available in the following languages. Links to translations of the first edition, available in 10 languages, are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared.
- Download English version [975 kB] (2022-06-06)1,2
- Download Czech version [910 kB] (2023-09-20)
- Download Farsi version [435 kB] (2023-07-20)
- Download French version [1.1 MB] (2023-09-20)
- Download German version [929 kB] (2023-09-20)
- Download Italian version [965 kB] (2024-01-15)
- Download Spanish version [709 kB] (2023-10-17)
Translation
Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.
Previous editions
The first edition of this information leaflet can be found here, in our publication archive. Selected translations of the first edition are listed below for convenience pending translation of the second edition.
- Download Finnish version (1st ed)
- Download Swedish version (1st ed.)
- Download Turkish version (1st ed.)
- Download Ukrainian version (1st ed.)
Notes
1. Dates show date of publication of the linked file on this website.
2. 2nd English edition first published 2022-07-30
All proficiency testing schemes include an assessment of laboratory performance. Most compare a laboratory result with an assigned value, and assess performance based on the difference and a criterion for successful performance. Often, this assessment also involves calculating a score for consistent interpretation across rounds and, sometimes, across PT schemes. But there are many different ways of determining an assigned value and setting a criterion for performance assessment, and there are several different scoring methods. 
The Eurachem Guide on “Selection, Use and Interpretation of Proficiency Testing (PT) Schemes” recommends participants to consider the statistical approach used by the PT provider when selecting a PT scheme. This leaflet is intended to help participants in quantitative PT schemes to better understand the statistical parameters that are used in the PT report to describe the distribution of results reported by participants.
The international standard ISO/IEC 17025 requires a laboratory to participate in proficiency testing (PT) and/or to participate in interlaboratory comparisons (ILCs) other than PT. However, the Standard gives no guidance as to what these other ILCs might be, or indeed how they might compare in relation to PT.