With the caveat that it's been a few years: while he touches on primary education, he spends more time on secondary. The focus is less on individual ROI, but so

With the caveat that it's been a few years: while he touches on primary education, he spends more time on secondary. The focus is less on individual ROI, but societal efficiency and policy: the core premise being that most secondary education is poor at increasing "human capital" (marketable skills, retained knowledge), and is instead valuable to employers because a college diploma is predictive for desirable hiring traits: conscientiousness, conformity, and grit. I have many disagreements with Caplan, particularly on economics, but I found it a worthwhile read.