Growth: With or Without Scale Effects?

December 15, 1998 -- Version 1.0 The property that ideas are nonrivalrous leads to a tight link between idea-based growth models and increasing returns to scale. In particular, changes in the size of an economy's population generally affect either the long-run growth rate or the long-run level of income in such models. This paper provides a partial review of the expanding literature on idea-based models and scale effects. It presents simple versions of various recent idea-based growth models and analyzes their implications for the relationship between scale and growth. Prepared for the AEA Meetings, January 3, 1999. Forthcoming in the AER Papers and Proceedings, May 1999.

Why Have Health Expenditures as a Share fo GDP Risen So Much?

Aggregate health expenditures as a share of GDP have risen in the United States from about 5 percent in 1960 to nearly 14 percent in recent years. Why? This paper explores a simple explanation based on technological progress. Medical advances allow diseases to be cured today, at a cost, that could not be cured at any price in the past. When this technological progress is combined with a Medicare- like transfer program to pay the health expenses of the elderly, the model is able to reproduce the basic facts of recent U.S. experience, including the large increase in the health expenditure share, a rise in life expectancy, and an increase in the size of health-related transfer payments as a share of GDP.

The Steady-State Growth Theorem: A Comment on Uzawa (1961)

This brief note revisits the proof of the Steady-State Growth Theorem, first provided by Uzawa (1961). We provide a clear statement of the theorem and a new version of Uzawa's proof that makes the intuition underlying the result more apparent.

Why Do Some Countries Produce So Much More Output per Worker than Others?

Output per worker varies enormously across countries. Why? On an accounting basis, our analysis shows that differences in physical capital and educational attainment can only partially explain the variation in output per worker we find a large amount of variation in the level of the Solow residual across countries. At a deeper level, we document that the differences in capital accumulation, productivity, and therefore output per worker are driven by differences in institutions and government policies, which we call social infrastructure. We treat social infrastructure as endogenous, determined historically by location and other factors captured in part by language.

The Value of Life and the Rise in Health Spending

Health care extends life. Over the past half century, Americans have spent a rising share of total economic resources on health and have enjoyed substantially longer lives as a result. Debate on health policy often focuses on limiting the growth of health spending. We investigate an issue central to this debate: can we understand the growth of health spending as the rational response to changing economic conditions---notably the growth of income per person? We estimate parameters of the technology that relates health spending to improved health, measured as increased longevity. We also estimate parameters of social preferences about longevity and the consumption of non-health goods and services. The story of rising health spending that emerges is that the diminishing marginal utility of non-health consumption combined with a rising value of life causes the nation to move up the marginal-cost schedule of life extension. The health share continues to grow as long as income grows. In projections based on our parameter estimates, the health share reaches 33 percent by the middle of the century.

The value of life and the rise in health spending

Health care extends life. Over the past half century, Americans spent a rising share of total economic resources on health and enjoyed substantially longer lives as a result. Debate on health policy often focuses on limiting the growth of health spending. We investigate an issue central to this debate: Is the growth of health spending the rational response to changing economic conditions - notably the growth of income per person? We develop a model based on standard economic assumptions and argue that this is indeed the case. Standard preferences - of the kind used widely in economics to study consumption, asset pricing, and labor supply - imply that health spending is a superior good with an income elasticity well above one. As people get richer and consumption rises, the marginal utility of consumption falls rapidly. Spending on health to extend life allows individuals to purchase additional periods of utility. The marginal utility of life extension does not decline. As a result, the optimal composition of total spending shifts toward health, and the health share grows along with income. This effect exists despite sharp diminishing returns in the technology of life extension. In projections based on the quantitative analysis of our model, the optimal health share of spending seems likely to exceed 30 percent by the middle of the century.

Life and Growth

Some technologies save lives — new vaccines, new surgical techniques, safer highways. Others threaten lives — pollution, nuclear accidents, global warming, the rapid global transmission of disease, and bioengineered viruses. How is growth theory altered when technologies involve life and death instead of just higher consumption? This paper shows that taking life into account has first-order consequences. Under standard preferences, the value of life may rise faster than consumption, leading society to value safety over consumption growth. As a result, the optimal rate of consumption growth may be substantially lower than what is feasible, in some cases falling all the way to zero.

Insurance and Incentives for Medical Innovation

This paper studies the interactions between health insurance and the incentives for innovation. Although we focus on pharmaceutical innovation, our discussion applies to other industries producing novel technologies for sale in markets with subsidized demand. Standard results in the growth and productivity literatures suggest that firms in many industries may possess inadequate incentives to innovate. Standard results in the health literature suggest that health insurance leads to the overutilization of health care. Our study of innovation in the pharmaceutical industry emphasizes the interaction of these incentives. Because of the large subsidies to demand from health insurance, limits on the lifetime of patents and possibly limits on monopoly pricing may be necessary to ensure that pharmaceutical companies do not possess excess incentives for innovation.

Intermediate Goods, Weak Links, and Superstars: A Theory of Economic Development

Per capita income in the richest countries of the world exceeds that in the poorest countries by more than a factor of 50. What explains these enormous differences? This paper returns to several old ideas in development economics and proposes that linkages, complementarity, and superstar effects are at the heart of the explanation. First, linkages between firms through intermediate goods deliver a multiplier similar to the one associated with capital accumulation in a neoclassical growth model. Because the intermediate goods' share of revenue is about 1/2, this multiplier is substantial. Second, just as a chain is only as strong as its weakest link, problems at any point in a production chain can reduce output substantially if inputs enter production in a complementary fashion. Finally, the high elasticity of substitution associated with final consumption delivers a superstar effect: GDP depends disproportionately on the highest levels of productivity in the economy. This paper builds a model with links across sectors, complementary inputs, and highly substitutable consumption, and shows that it can easily generate 50-fold aggregate income differences.