This was shown both for splitting the participant group in two halves on the basis of vocabulary size (i.e., with translation performance as criterion) and for excluding participants below a certain proficiency criterion.
As a proficiency measure, we used the average of the self-reported proficiencies across all reported languages by a subject.
Of 31 laboratories, 14 (45.2%) met all proficiency criteria.
Seventeen laboratories missed the proficiency criteria because of a lack of sensitivity.
For their successful implementation, appropriate proficiency criteria must be developed.
An assumption was that asymptotes in performance as a function of training year can be used to set the proficiency level for a technical skill, so the value at which the asymptote occurs can be labeled as the proficiency criteria.
This test was preferred as it is freely available, can be administered in a short time frame, and the results can easily be cross-referenced with other standardised tests such as IELTS® or proficiency criteria such as the Common European Framework (Council of Europe, 2001).
The proficiency criteria were established by experts in previous studies of construct validity and learning curves.
Applying the proficiency criteria, 51 (88%) of 58 laboratories passed the minimum requirements for successful participation.
Applying the proficiency criteria of this study, only eight laboratories correctly analysed all samples with their respective EIA, IFA or NT methods.
Compared to an earlier study on molecular testing for filoviruses, Lassa virus, and orthopoxviruses, using very similar proficiency criteria (15 ), almost double the portion of participating laboratories completed the study successfully (88% vs. 45.8%).
