Statistics

Our statistical treatments meet the requirements of the current normative documents, namely :

• ISO guide 43 describing guidelines for the implementation of proficiency tests;
• ISO guide 35 detailing the general and statistical principles of data processing for proficiency tests;
• ISO 5725 standard – "Accuracy (trueness and precision) of measurement methods and results".

Thus, thanks to robust statistical methods, a reference value for each studied parameter is determined. This value is based on the consensus of participants results collected during the reasonable period to start the sample treatment. Each laboratory can then be positioned relative to this reference value by an evaluation of its analytical performances expressed in terms of z-score and qualitative ranking.

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Your test report

A test report is issued several weeks after the proficiency test is closed. This report presents the conduct of the proficiency test and the results of the statistical processing with data given by the participants.

A first part of the test report mentions important information describing the test: the list of implemented parameters the contact details of the laboratory responsible for the sample preparation as well as details regarding their preparation.
Then, the quality of test materials, that means the results of stability and batch homogeneity testing, is indicated. These results are interpreted and possible problems underlined.

The second part of the test report summarizes the results of the data statistical treatment. Synthesis tables present the reference value and precision values :

• concentration level m (mean value of the test) ;
• repeatability r ;
• reproducibility R ;

The final part summarizes using tables and graphs the overall results of the statistical analysis. Each participant will find his results in terms of z-scores and qualitative ranking.

Download : General Information.pdf (paragraph 2.3 Statistical processing) For more information : Contact us