The alteration of the PISA sample in Catalonia far exceeds that of any country in the latest report

Source Summary

This Friday, the Department of Education communicated that, due to an error, Catalonia's results in the PISA tests will not be valid for comparison with other territories nor with Catalan results from previous years. The reason is that when deciding how many students did not take the tests due to learning difficulties, Catalonia exceeded the limit: it discarded 23% of the students in the sample when the OECD marks that the maximum number of exempted students cannot exceed 5%.