The statistical evaluation of the interlaboratory comparison is defined in ISO 13528 and ISO 5725-2.
156 testing laboratories from 37 countries all over the world participated in 64 individual test methods in the last proficiency test OFI-pts2018.
| Austria | Norway |
| Bangladesh | Poland |
| Belgium | Portugal |
| Brasil | Romania |
| China | Saudi Arabia |
| Colombia | Slovakia |
| Costa Rica | Slovenia |
| Croatia | South Korea |
| Czech Republic | Spain |
| France | Sri Lanka |
| Germany | Sweden |
| Great Britain | Switzerland |
| Greece | Thailand |
| Hungary | The Netherlands |
| Iran | Turkey |
| Italy | United Arab Emirates |
| Japan | USA |
| Latvia |
Evaluation parameter
Outlier according to Grubbs’ test
Outlier according to Cochran’s test
z-score
Youden-Plot (Scatter diagram)
