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PT evaluation software A45

In September 2003 the German standard DIN 38402 - A45 "Ringversuche zur externen Qualitätskontrolle von Laboratorien" was published and revised in 2014. In this standard robust statistical methods are used for the calculation of nthe standard deviation and a consensus mean and zU are used for the assessment of the values. These methods have also been introduced into ISO/TS 20612:2007.
AQS Baden-Württemberg has written an evaluation programme on the basis of an EXCEL-Macro. This programme is sold by the "Transfer- und Gründerunternehmung Qualitätssicherung in der Chemischen Analytik" of the TTI GmbH at the University of Stuttgart for € 500,-- plus VAT (if applicable).
If you are interested please contact AQS Baden-Württemberg directly ( Mail toinfo@aqsbw.de).


The macro can be used for the statistical evaluation of PTs according to DIN 38402 - A45:9/2003 and ISO/TS 20612:2007 respectively.
The Q method is used to calculate the standard deviation and the hampel estimator is used for the calculation of the mean.
Both are robust statistical methods.


The following figure show a screenshot of the programme:

The white cells can be used to enter data. Column A is intended to contain the identification (code) of the lab, columns B to G the results of up to 6 results from multiple measurements,cell L2 is for the identification of the PT and cells L3 for the identification of the sample.
By clicking on "calculate" the statistical calculation are started and afterwards its results are shown in the cells L5 to L8 and N5.
The assessment of the laboratory mean is done using zU-scores, calculated on the basis of the Hampel estimator and the Q method standard deviation. If the assessment shall be based on a reference value, it can be inserted in cell L10. If the standard deviation for proficiency assessment is to be limited, upper and lower limits can be entered in cells L11 and L12. If a fixed standard deviation for proficiency assessment is to be used, this value has to be entered in both cells (L11 and L12).

System requirements

The macro is based on © Microsoft EXCEL. So the system requirements for this programme apply.