"“Socio-economic background did play a role in the test scores, accounting for 12 percent of the variation in reading performance in each country, on average. But the results also showed that the poorest 10 percent of students in China still outperformed the OECD average. That’s perhaps surprising for a country with an average household net adjusted disposable income per capita that’s about three times less than the OECD average of about $30,500.”