Understanding PT statistics

Details

Published: Tuesday, 21 May 2024 19:59

Content

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.

Availability

The leaflet is currently available in English.

• Download the English version (670 kB) (2024-05-21)¹

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Notes

1. Dates show date of publication of the linked file on this website.

Understanding PT performance assessment

Details

Published: Tuesday, 21 May 2024 19:59

Content

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. 

This leaflet is intended to help participants in quantitative proficiency testing (PT) schemes to better understand the performance assessment made by the PT provider.

Availability

The leaflet is currently available in English.

• Download the English version (730 kB) (2024-05-21)¹

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Notes

1. Dates show date of publication of the linked file on this website.

Information leaflets

Details

Published: Wednesday, 10 April 2024 22:52

Eurachem Information Leaflets are short briefing documents on a specific topic. Information leaflets are usually intended to inform a wide audience, including laboratory staff, managers and laboratory customers.

Like Guides, Information Leaflets are developed by the different Working Groups, often in cooperation with other organisations.

Eurachem information leaflets are all available free of charge from the website. Many have been translated into several languages.

Current Eurachem Information Leaflets

The current list of topics and information leaflets is given below. All leaflets are available in English; availability in additional languages is indicated below. "Translations available" indicates that more than four language versions (including English) are available.

Previous editions, which may be available in additional languages, can be found in our publication archive.

Accreditation

• ISO/IEC 17025:2017 - A New Accreditation Standard (2018) | Translations available

Proficiency testing

• Proficiency Testing Schemes and other interlaboratory comparisons (2022) | Translations available (1st ed)
• How can Proficiency Testing help my laboratory? (2022) | Translations available
• Selecting the right proficiency testing scheme for my laboratory (2022) | Translations available
• Proficiency testing - How much, and how often? (2022) | Translations available (1st ed)
  
• Pre- and post-analytical proficiency testing (2022) | Translations available
• PT Schemes for sampling (2020) | Translations available
• Use of surplus Proficiency Test items (2022) | Translations available
• How to investigate poor performance in proficiency testing (2022) | Translations available
• Understanding PT performance assessment (2024)
• Understanding PT statistics (2024)
• Let's call a PT scheme a PT scheme! (2022) | Farsi, Italian
• Interlaboratory Comparisons other than PT (2024)

Measurement uncertainty and traceability

• Information leaflet for lab customers concerning the quality of chemical analyses (2000) | German, Portuguese, Turkish
• Traceability of Analytical Results (2019) | Translations available
• Use of uncertainty information in compliance assessment (2021) | Farsi, German, Ukrainian
• Using repeated measurements to improve the standard uncertainty (2015) | Translations available
• Treatment of an observed bias (2017) | Translations available
  
• Setting target measurement uncertainty (2018) | Translations available
• What is the uncertainty factor? (2021) | German, Farsi

Method validation

• The importance of method validation (2021) | Farsi, German, Turkish

Terminology

• You talk, we understand – The way out of the tower of Babel
  An introduction to terminology in measurement (2023)

Withdrawn and Superseded Information Leaflets

Some older Eurachem Information leaflets have been superseded by the current editions listed above or withdrawn as no longer of current interest. Available electronic copies of all superseded guidance are, however, listed in the Publication Archive for reference.

Interlaboratory comparisons other than proficiency testing

Details

Published: Wednesday, 10 April 2024 22:51

Content

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.

This leaflet, prepared by the EEE-PT Working Group, outlines other types of interlaboratory comparison and points out some of the limitations as compared to PT.

Availability

• Download English version (551 kB) (Published 2024-04-11)^1,2

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Notes

1. Publication dates are dates of website publication for the current version.

2. First published 2024-04-10. Current file version (Ed.1a) includes editorial correction to date of publication.

Let's call a PT scheme a PT scheme!

Details

Published: Sunday, 29 May 2022 23:00

Content

Interlaboratory comparisons (ILCs) have been used for more than a century and many important concepts are linked to them.

This leaflet, prepared by the Eurachem PT Working Group, addresses the basic terminology of ILCs, explains why some colloquial terms can be misleading or misunderstood, and the importance of harmonisation..

Availability

• Download English version (375 kB) (Published 2022-07-29)^1,2
• Download Farsi version (295 kB) (Published 2023-07-20)
• Download Italian version (415 kB) (Published 2024-01-15)

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Notes

1. Publication dates are dates of website publication for the current version.

2. English version (V1) first published on this site on 2022-05-30. Amendment V1a (editorial amendment only) added 2022-07-29.

What is the uncertainty factor?

Details

Published: Friday, 14 May 2021 23:00

Content

Appropriate expression of the measurement uncertainty (MU) is crucial, and there are situations when the traditional, symmetric, expanded uncertainty interval is not sufficient. This leaflet aims to explain the concept of the uncertainty factor and how it can be used to provide a convenient and realistic uncertainty interval in particular circumstances..

This leaflet was produced by the Eurachem Sampling Uncertainty Working Group and the Royal Society of Chemistry Analytical Methods Committee (AMC) Sampling Uncertainty Working Groups.

Availability

• Download English version (PDF, 341 kB) (Published 2021-05-14)*
• Download Farsi version (PDF, 324 kB) (Published 2023-05-23)
• Download German version (PDF, 462 kB) (Published 2021-11-11)

Translation

Please consult the Eurachem Sampling Uncertainty Working Group Chair, directly or by using the UfSWG contact form, if you would like to prepare a translation in your own language.

*Publication dates are dates of website publication. English version first published on this site on 2020-07-29.

Use of uncertainty information in compliance (2021)

Details

Published: Thursday, 29 April 2021 14:31

Content

This information leaflet is intended for laboratories perfoming chemical analyses. It has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group (see here for details) to introduce the use of decision rules and guard bands in interpreting results accompanied by measurement uncertainty information. The leaflet summarises the principles described in the Eurachem Guide "Use of uncertainty information in compliance assessment", which is available here.

This revised edition of this information leaflet is amended to reflect changes in the second edition of the compliance Guide.

Availability

• View the leaflet in English (pdf, 132 kB) (Published* 2021-04-29)
• View the leaflet in Farsi (pdf, 323 kB) (Published 2021-12-09**)
• View the leaflet in German (pdf, 449 kB) (Published 2021-11-11)
• View the leaflet in Ukrainian (pdf, 252 kB) (Published 2022-07-31)

* Publication dates are dates of publication on this website.

** First published 2021-09-01; amended 2021-12-09.

Translation

Translation into other languages is encouraged for members of Eurachem. Other offers of translation should be directed to the Eurachem Secretariat for permission. The Eurachem policy on maintenance and development of Eurachem guidance, available on the Policies page, gives further information on translation.

Note: The previous (2015) edition is available in English, Czech, Estonian, Finnish, Portuguese, Turkish and Ukrainian.

Previous editions

The previous edition of this leaflet can be found here.

The importance of method validation

Details

Published: Thursday, 25 February 2021 16:05

Content

Method validation is an important requirement in the practice of analytical science. ISO/IEC 17025, OECD guidelines on Good Manufacturing Practice and many similar codes of practice require some level of validation, whether by verification of the laboratory's implementation of published standard methods, or by comprehensive validation studies of new, in-house, procedures. Most analytical chemists are aware of its importance, but why it should be done, when, and exactly what needs to be done, is not always clear.

This leaflet, prepared by the Eurachem Method Validation working group, gives a brief introduction to the overall process of validation and the key performance characteristics to be studied, and provides pointers to more detailed guidance.

Availability

• Download the leaflet in English (PDF, 273 kB) (Published 2021-02-25)*
• Download the leaflet in Farsi (PDF, 227 kB) (Published 2021-11-29)
• Download the leaflet in German (PDF, 728 kB) (Published 2021-11-11)
• Download the leaflet in Turkish (PDF, 485 kB) (Published 2021-05-10)

Translation

Please consult the Method Validation Working Group if you would like to prepare a translation in your own language.

*Publication dates are dates of website publication. English version first published on this site on 2021-02-25.

Investigating poor performance in proficiency testing

Details

Published: Tuesday, 07 January 2020 17:00

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

Top^^

Proficiency testing schemes for sampling

Details

Published: Tuesday, 07 January 2020 17:00

Content

Proficiency Testing schemes for sampling play an important role in the improvement of sampling procedures and also in the development of participants from an educational point of view, especially if workshops with the participants are organised. PT schemes for sampling can also give an appreciation of the contribution of the sampling in relation to the overall quality of the measurement, including the associated contribution to the measurement uncertainty.

This leaflet, prepared by the EEE-PT Working Group, gives some hints on the application of ISO/IEC 17043 for PT providers organising PT schemes for sampling. If there is a comparison between participants and a mechanism for performance evaluation which meets the objective of the PT scheme for sampling, then ISO/IEC 17043 is applicable.

Availability

• Download English version (Published 2020-07-29)^1,2
• Download Czech version (Published 2021-10-07)
• Download Farsi version (Published 2022-03-01)
• Download French version (Published 2021-02-23)
• Download German version (Published 2021-02-23)
• Download Italian version (Published 2020-11-30)
• Download Swedish version (Published 2020-10-23)
• Download Turkish version (Published 2021-02-26)
• Download Ukrainian version (Published 2020-10-12)

Translation

Please consult the PT Working Group Chair if you would like to prepare a translation in your own language.

Notes

1. Dates show date of publication of the linked file on this website.

2. 2nd English edition first published 2020-07-29

Top^^