There is a statistically significant positive relationship between teacher salaries relative to GDP per capita and PISA 2012 math scores in economies with GDP per capita of more than US$20,000 …

„Analysis of PISA results suggests that the only type of resource that is correlated with student performance is teacher salaries relative to national income. There is a statistically significant positive relationship between teacher salaries relative to GDP per capita and PISA 2012 math scores in economies with GDP per capita of more than US$20,000.“

World Bank Group (Hrsg.), „Growing Smarter“ (2018), S. 113