Education is yet another of the inputs to human capital, as are health care and immigration –content Inputs to human capital Education is yet another of the inputs to human capital, as are health care and immigration. We understand generally that investments in education improve household, individual, and state level incomes, but there is some question as to whether or not the benefit of these additional investments are sufficient to justify the costs. In developed nations, the United States in particular, increased investments in education in recent decades have provided ambiguous results, suggesting that the marginal return is not always positive and that further investments may not provide the necessary returns. Further, in periods where decreased per pupil investments in education are observed in the United States the effects are statistically significant and highly positive, reflecting that decreases in these investments result in decreased income and outcomes generally. The net effect of these findings offers at least two possible conclusions: 1) while increased investments in education may not be positive, they may be necessary to maintain the nation’s already relatively highly skilled human capital stock, and 2) the national education infrastructure is brittle and subject to a human capital depreciation effect absent sustained levels of per pupil investment. BTW what is not ambiguous is that increased educational attainment directly leads to increased income at the individual level; just as it improves a variety of other utility enhancing outcomes. So… how might we go about using education to improve the human capital stock which is to ask, how might we increase productivity via education without simply throwing more money at it?