Data evaluation and reports

Fast evaluation

We publish the target values of synthetic samples on our website latest on the second working day after the closing date for result submission.
Within about two weeks, the proficiency test data will be evaluated and the reports will be prepared.

Every laboratory will receive a confirmation of participation per letter. It contains the name, the letter code of the laboratory, the number of the round, the target values, the results, the recoveries, the z-score-criteria(s) and the achieved z-scores.

The participants can download the reports via Internet.

Target values

Mass concentrations determined by weighing certified standards and high-purity salts are generally used as target values for the parameters to be examined. Exceptions to this rule are presented in the respective reports. 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. The calculation of recovery, laboratory mean values and statistical characteristics refers to the target values, which, with a few exceptions (e.g. conductivity, KMnO4-index) are independent of the results and the number of participants. This preserves the complete information content of the evaluation.
Quick preparation of the reports enables fast evaluation of the analytical performance and provides the possibility for the participants to take corrective actions.

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 target values can be calculated, are arranged in the categories "false negative", "false positive" or "non-classifiable" and are illustrated as such.

Report Design

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 as well as an example for calculating the z-score.

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. For comparison with the previous average performance of the other laboratories, the z-scores are shown in the tables next to the recoveries. A summary of all z-scores can be found in the tables of the parameter-oriented part.

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

Questions, suggestions, complaints, objections

In order to be able to complete the proficiency test rounds in a foreseeable period of time, we ask you to observe the deadline in case of an objection. It ends six weeks after the closing date. The dates for the respective round can be found in the detailed programme for the parameters. Please inform yourself about the objection deadlines valid at the Environment Agency Austria (UBA).

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