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Selecting the right proficiency testing scheme for my laboratory

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Published: Thursday, 28 May 2015 12:54

Content

EURACHEM through its Proficiency Testing Working Group has produced an information leaflet to help laboratories select the most appropriate proficiency testing schemes. Several PT schemes are often available for the same area of testing, so this leaflet focuses on key questions that can help laboratories choose those PT schemes that are best suited for their needs.

This second edition updates the leaflet to reference current guidance on PT.

Availability

The second edition is currently available in the following languages. Links to translations of the first edition, available in 14 languages, are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared.

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.

Notes

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

2. 2nd English edition first published 2022-07-30

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Using repeated measurements to improve the standard uncertainty

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Published: Sunday, 11 July 2010 16:39

Content

Analysts often take multiple observations, and sometimes average the result of several observations to reduce the uncertainty associated with random variation. However, it is often unclear how the standard uncertainty associated with averaged results should be calculated from an observed standard deviation. Sometimes one should divide by the square root of the number of observations; sometimes the standard deviation is used unchanged, and sometimes some alternative formula is appropriate. 

This information leaflet has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group (see here for details) to give further explanation of when the classical 'root n' formula can, and can not, be used. The leaflet amplifies principles described in the Eurachem Guide "Quantifying uncertainty in analytical measurement", which is available here.

 

Availability

*2015 edition

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.

Amendment history

This leaflet was amended to improve clarity in April 2016. The previous English version, as issued in 2015, is available for comparison.

Treatment of an observed bias

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Published: Sunday, 11 July 2010 16:39

Content

bias img 240x194Bias is routinely determined during the validation of analytical methods. Usually, the observed bias is not exactly zero. It is then important to decide whether the observed bias can reasonably be treated as unimportant, or whether some further action needs to be taken. This can be particularly difficult to decide when applying the principles of the 'Guide to the Expression of Uncertainty in measurement', which assumes that a correction has been applied for any important bias. 

This information leaflet has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group (see here for details). The leaflet discusses whether or not an observed significant bias should be corrected and the impact this may have on the measurement uncertainty (MU). The leaflet does not describe how to apply a correction or how to increase the uncertainty to take account of an uncorrected bias, though it does provide relevant literature sources.

 

Availability

 * 2nd printing; editorial amendment only

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.

Publication date

This leaflet was first published in English on 2017-05-27.

* The English copy on this page is a minor (editorial) amendment, published 2022-10-21; the recommendations are unchanged.

Traceability of Analytical Results

Details
Published: Sunday, 11 July 2010 16:35

Content

Octopus 1 195x182This information leaflet is intended for laboratories perfoming chemical analyses. It has been prepared by the Eurachem Measurement Uncertainty and Tracability Working Group to summarise the principles of metrological traceability in routine testing. It follows the general principles of the Eurachem Guide "Traceability in Chemical Measurement", which is available here.

The leaflet was first issued in 2005. A revised version, updated for relevance to ISO/IEC 17025:2017, was published in 2019.

Availability

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.

Previous editions

Earlier editions of this leaflet, including translations in Spanish and Portuguese, can be found in the publication archive.

Pre- and Post-analytical PT

Details
Published: Sunday, 11 July 2010 16:34

Contents

prepost80EURACHEM through its Proficiency Testing Working Group has produced an information leaflet on Pre- and post-analytical proficiency testing aimed at PT participants and their customers. This second edition is an editorial revision.

Availability

The second edition is currently available in the following languages. Links to translations of the first edition are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared.

* Dates are the date of addition to this website

Translation

Translation into other languages is under way via the PT Working Group. 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 is available here. Selected translations of the first edition are listed below for convenience, pending translation of the second edition.

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

2. 2nd English edition first published 2022-07-30

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Proficiency Testing

Details
Published: Sunday, 11 July 2010 16:32

Content

EURACHEM through its Proficiency Testing Working Group has produced an information leaflet on proficiency testing aimed at PT participants and their customers. This second edition is an editorial revision.

The second edition is currently available in English. Links to translations of the first edition, are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared. 

Availability

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.

 

Notes

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

2. 2nd English edition first published 2022-07-30

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How can PT help my laboratory? (2022)

Details
Published: Sunday, 11 July 2010 16:32

Content

EURACHEM through its Proficiency Testing Working Group has produced an information leaflet explaining how proficiency testing can help to monitor and improve laboratory quality. This second edition updates the leaflet to reference current guidance on PT.

Availability

The second edition is currently available in the followng languages. Links to translations of the first edition in other languages are temporarily maintained on this page (below) for convenience while translations of the second edition are prepared.

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.

 

Notes

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

2. 2nd English edition first published 2022-07-30

 

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Measurement Uncertainty for Laboratory Customers

Details
Published: Sunday, 11 July 2010 16:25

Contents

This information leaflet is intended for customers of laboratories perfoming chemical analyses.The leaflet tells customers why laboratories report measurement uncertainty.  It is based on the Swedish leaflet SP INFO 2000:23 which was prepared by SP and FaL in collaboration with the Swedish EPA, The Swedish National food Administration, VAV and Swedac, with support from the Swedish SME-project KMoo P0 07313. The English version on this website has been prepared together with Eurachem, Eurolab, EA and EMPA.

Availability

Translations

Translation into other languages is permitted for members of Eurachem, by kind permission of RISE, Sweden (formerly SP). Please contact the MU&T WG Secretary to confirm permission and for source files.