The returns to primary education (whether social or private) are the highest among all educational levels… Top priority should be given to primary education as a form of human resource investment.
Psacharopoulos, 1981, p.326, p.333
Such studies had considerable influence at the World Bank and contributed to a reduction in funding for higher education in many countries. Fast forward 33 years:
[T]here is evidence to suggest that [tertiary education] may provide greater impact on economic growth than lower levels of education… [Tertiary education] contributes to the strengthening of institutions, and the forming of professionals in key areas, such as education and healthcare. The diverse functions of the university, in addition to its direct impact on economic growth, should be acknowledged and supported.
Oketch et al, 2014, p.8
Today higher education is featured in the Sustainable Development Goals, including targets on access to affordable and quality university education and increasing the number of scholarships to low income countries. Notably absent in the Millennium Development Goals, these targets follow a renewed acceptance of the role higher education can play in overall development, even for the poorest countries.
Of course it would be a mistake to drive policy solely by measuring economic returns, or to view primary, secondary or tertiary education in isolation. Education is a continuum, and higher education has a role to play in strengthening the stages that come before it, not least through teacher training. Nonetheless, 33 years can make quite a difference.