Growth impacts of Australian and UK university education

I reviewed some regressions connecting university student inflows into Australia and the UK with economic growth in the countries sending them. It turned out that on average, Australian education is associated with three times the growth increase as UK education.

Perhaps Australian education is much more economically productive than UK education. But the statistic on its own doesn't say that. Other factors which may influence the relation are whether students return home after they complete their courses, the type of education, institutional factors facilitating the use of education, motivations for taking or providing education, regional origin since Australia attracts more students from high growth Asian countries, and causality since we had to use OLS as the student data was only available for one year.