The methods of the PISA study are quite controversial. It doesnt even properly control for immigration and background and the fact how its presented to pupils.
In Germany in the schools I know of, its stressed a lot how it does NOT affect anything at all, so its not actually a test on ability, but also on ability to motivate oneself to perform well in a meaningless test.
In Germany in the schools I know of, its stressed a lot how it does NOT affect anything at all, so its not actually a test on ability, but also on ability to motivate oneself to perform well in a meaningless test.