# **Conclusions**

The impacts of a population’s health on national income are hotly debated, and they probably vary depending on the health indicator used and the countries included in the analysis. Some cross-country regressions using instrumental variables find quite large impacts of health on income, but few other analytical approaches yield similar results. Part of the problem in resolving the debate lies in the fact that comparisons of health and nonhealth interventions in nonexperimental environments are besieged by identification problems, while (quasi) experimental settings that would allow such comparisons are especially rare. It is difficult enough to estimate the impact of a health _or_ growth intervention compared with the status quo, but comparing health _and_ growth interventions has proven especially intractable, particularly in light of the vast array of interventions that are feasible in both areas.

The two empirical approaches to this dilemma have been, first, to estimate the effects of arguably exogenous innovations in population health status on incomes at the macro level and, second, to focus at the micro level on the impact of specific health interventions on economic outcomes.

At the macro level, our tentative conclusion is that the effect of health on income is small if it exists at all and that the results are ambiguous, largely because of the methodological challenges discussed above. National public health investments such as environmental cleanup or vaccinations show an impact on overall health status and are associated with improved investment opportunities that contribute to growth. At the micro level, clear causal relationships have been documented from health to earning potential and income.

Although the macro analyses seek to provide information on the impacts of improved health on aggregate incomes, they cannot really tell us whether an extra dollar of public funding should be allocated to the health sector or to an alternative or which interventions provide the biggest bang to health _and_ income for the buck. Our reading of the literature suggests that some health policies and investments, particularly those with pure public-good attributes, can plausibly have important impacts on incomes, but that at the macro level health and incomes are at least as likely to be jointly determined by such intangible features as institutional quality, corruption, and public sector accountability.

Nevertheless, micro studies provide solid guidance on marginal benefits and on some of the tradeoffs across investments at the individual and household levels. Factors that foster greater productivity and higher wages are nutrition, early childhood education (both cognitive and noncognitive), education more generally, and mother’s education in particular. Public health investments that eliminate pathogens raise health status and expand access to agricultural land, translating into enhanced learning and rising agricultural yields, respectively, and serving to raise productivity, labor supply, and earnings. Much remains to be done, however, on ensuring the benefits of medical interventions and investing to improve their effectiveness and impact.

The lack of clarity about the macroeconomic link from health to economic growth is not a reason to refocus public investment away from the health sector. The link from growth to health itself takes many forms, and it would seem to be a mistake to put all our eggs in the growth basket if 30