Ok, but the test results from the PISA will be a combination of factors: a certain portion attributable to familiarity with the content, a certain portion attri

Ok, but the test results from the PISA will be a combination of factors: a certain portion attributable to familiarity with the content, a certain portion attributable to general IQ, a certain portion attributable to teaching methods, a certain proportion attributable to societal factors (urbanisation/distribution of wealth), and a certain portion attributed to general strategies and cultural familiarity in a testing environment. An obsession with testing would most certainly explain a statistical bump, but I imagine neither you nor I can accurately attribute how much each of those things contributes to the PISA score of each country. Now if i really wanted to be culturally insensitive, i'd add in a portion for preponderance to cheat to show themselves in a good light. But good luck ever getting governments together to try to accurately measure that...