Evaluation

The Institute for Quality Assurance evaluates the data promptly and places the evaluation online on the quality assessment portal. This includes the results of each participant (only available for the corresponding participant), a statistical total evaluation with anonymous and summarized results of all participating laboratories, and further helpful information (e.g. images from immunofluorescence tests, blot strips). Participants receive a message as soon as the evaluation report is available.
Qualitative evaluation is crucial for the granting of a certificate. If the qualitative results of the participant for all samples are in agreement with the expected values, the quality assessment scheme has been passed and a certificate will be issued.
If in normal practice a confirmatory test is performed because of results obtained in a screening test then this must also be performed. If it is not performed, then even if the correct result is obtained for the screening test no certificate will be issued.
If a quality assessment scheme is not passed, the participant receives a confirmation of participation rather than a certificate. Certificates and confirmations of participation are sent to participants by post. 
In the individual evaluation report for each participant, the following statistical information is given alongside the participant’s results and the expected results. These values are based on all participants who used the same test system.

• Median of results*
• 68% result range*
• Number of participants
• Percentage of correct results (pass rate)

*with positive samples, if at least 6 participants gave a quantitative result

The median is the middle value of all measurement values when sorted by size, so that half of the values lie under the median and half over. If the number of measurement values is even, the arithmetic mean of the two middle values is taken as the median.
The median rather than the arithmetic mean is used as a statistical parameter to reduce the influence of extreme values. Outlier tests are not performed.
The 68% result range gives the distribution range of quantitative results, within which the measurement values of 68% of the participants lie.
In the general evaluation report the following information is given for each test that was used by participants in the quality assessment scheme:

• Number of participants
• Percentage of correct results (pass rate)