Data evaluation and reports

Fast evaluation

We publish the reference values of synthetic samples on our website on the first working day after the closing date for result submission. Afterwards, we evaluate and summarise the analytical data and prepare a final report within two weeks.

Every laboratory will receive a confirmation of participation per regular mail. It contains the name and the letter code of the laboratory, the number of the round, the reference values, the results, the recoveries, the z-Score-criteria (s) and the achieved z-Scores.

The participants can download the reports via Internet. A printed hard copy of the report must be explicitly ordered and is charged with € 40,- per round. It is possible to order hard copies at any time.

Reference values

Data evaluation is based on reference values, which are obtained from gravimetric data of the sample preparation. All results submitted to the IFA-Tulln are subjected to an outlier test (according to Hampel). Data identified as outliers are rejected prior to the calculation of further statistical characteristics such as laboratory average values, standard deviations between laboratories´ results and recoveries of the reference values. Quick preparation of the reports enables fast evaluation of the analytical performance and provides the possibility for the participants to take corrective actions.

Report Design

The evaluation of the results is descriptive rather than prescriptive. Up to now, the reports mainly illustrated the data of the participants and did not contain any real marks for the participant's performance. However, we include z-Scores based on long-term performance data of our participants in our evaluation. Additionally, every laboratory receives a sheet with the achieved z-scores by letter. For each parameter the z-Scores are illustrated in both tabular and graphical form.

The report contains recovery and deviation diagrams, thus presenting the data in an illustrative and easily understandable way. Results, from which no recoveries of the reference values can be calculated, are arranged in the categories "false negative", "false positive" or "non-classifiable" and are illustrated as such.

The series report consists of three sections:

The text gives general information about the series, a description of the sample composition and a short summary of the results.

The parameter-oriented part of the report contains a summary of all results (raw data tables) and the results sorted according to parameters. For each parameter the transmitted results of all participating laboratories are illustrated in both tabular and graphical form.

In the third part of the report the results of each laboratory are shown. The recoveries and deviations from the reference values are presented in both tabular and graphical form. This type of data illustration enables rapid estimation of the own analytical performance.

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