Your source fiddled with the PISA numbers for the USA to exclude all students of non-European descent. I'm not sure what s/he was trying to prove.
It's trying to prove that US schools are just as good at educating European Americans as German schools are at educating Europeans. (Sanandaji also excluded immigrants from the German numbers.)
I.e., any gaps in output between US and German schools are caused by gaps in the input, not the school system itself.
It's trying to prove that US schools are just as good at educating European Americans as German schools are at educating Europeans. (Sanandaji also excluded immigrants from the German numbers.)
I.e., any gaps in output between US and German schools are caused by gaps in the input, not the school system itself.