controlling for the heterogeneity in the skill (education) measurement is essential. The heterogeneity stems from the raw data, which measures skills by years of schooling, disregarding differences in the quality of schooling. To address this potential problem, all the migration stocks and rates are adjusted for quality of education. using Hanushek and Woessmann's (2009) new measures of international differences of cognitive skills aver- age international assessment of student achievement in 12 international student achievement tests (ISATs).