Changes in Yield Stability: Wheat and Maize in Developing Countries

This study asks whether the diffusion of modern varieties has affected the yield stability of wheat and maize production in developing countries between 1960 and 2004. The data suggest strongly that, over the past forty-plus years, there has been a striking decline in the relative variability of grain yields in wheat and (to a lesser extent) maize. The declines are strongest when measured as the standard deviation of yield divided by the mean, but there have also been declines in other measures of variability, such as the percentage deviation from trend. Declines in yield variability do not appear to be driven by increases in intensification (e.g., irrigation), nor do they appear to extend to crops, such as oilseeds, in which there has been little concerted public sector breeding effort. Instead, they appear to reflect changes in the portfolio of varieties being grown, possibly in response to breeding efforts aimed at disease and pest problems. By reducing the fluctuations in grain yields, researchers may have played a significant role in making modern crop technology attractive and accessible to farmers around the globe.Crop Production/Industries,

Getting Income Shares Right

Many widely used economic models implicitly assume that income shares should be identical across time and space. Although time series data from industrial countries appear consistent with this notion, cross-section data generally appear to contradict the assumption of constant income shares. A commonly used calculation suggests that labor shares of national income vary from about 0.05 to about 0.80 in international cross-section data. This paper suggests, however, that this widely used approach underestimates the labor income of the self-employed and other proprietors. Several adjustments for calculating labor shares are identified and compared. All of them yield data that appear broadly consistent with the hypothesis that labor shares for most countries fall in the range of 0.65 to 0.80self employment, factor shares, income shares, labor shares

Impacts of International Research on Intertemporal Yield Stability in Wheat and Maize: An Economic Assessment

Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Global Climate Change and the Resurgence of Tropical Disease: An Economic Approach

We study the impact of global climate change on the prevalence of tropical diseases using a heterogeneous agent dynamic general equilibrium model. In our framework, households can take actions (e.g., purchasing bednets or other goods) that provide partial protection from disease. However, these actions are costly and households face borrowing constraints. Parameterizing the model, we explore the impact of a worldwide temperature increase of 3°C. We find that the impact on disease prevalence and especially output should be modest and can be mitigated by improvements in protection efficacy.DSGE models, climate change, tropical diseases, incomplete markets

Global Climate Change and the Resurgence of Tropical Disease: An Economic Approach

We study the impact of global climate change on the prevalence of tropical diseases using a heterogeous agent dynamic general equilibrium model. In our framework, households can take actions (e.g., purchasing bednets or other goods) that provide partial protection from disease. However, these actions are costly and households face borrowing constraints. Parameterizing the model, we explore the impact of a worldwide temperature increase of 3 degrees Celsius. We find that the impact on disease prevalence and especially output should be modest and can be mitigated by improvements in protection efficacy.

Agriculture, Roads, and Economic Development in Uganda

A large fraction of Uganda's population continues to earn a living from quasi-subsistence agriculture. This paper uses a static general equilibrium model to explore the relationships between high transportation costs, low productivity, and the size of the quasi-subsistence sector. We parameterize the model to replicate some key features of the Ugandan data, and we then perform a series of quantitative experiments. Our results suggest that the population in quasi-subsistence agriculture is highly sensitive both to agricultural productivity levels and to transportation costs. The model also suggests positive complementarities between improvements in agricultural productivity and transportation.

Global Climate Change and the Resurgence of Tropical Disease: An Economic Approach

We study the impact of global climate change on the prevalence of tropical diseases using a heterogeneous agent dynamic general equilibrium model. In our framework, households can take actions (e.g., purchasing bednets or other goods) that provide partial protection from disease. However, these actions are costly and households face borrowing constraints. Parameterizing the model, we explore the impact of a worldwide temperature increase of 3° C. We find that the impact on disease prevalence and especially output should be modest and can be mitigated by improvements in protection efficacy.DSGE models, climate change, tropical diseases, incomplete markets

Malaria: Disease Impacts and Long-Run Income Differences

The World Health Organization (WHO) reports that malaria, a parasitic disease transmitted by mosquitoes, causes over 300 million episodes of “acute illness" and more than one million deaths annually. Most of the deaths occur in poor countries of the tropics, and especially sub-Saharan Africa. Most of the countries with high rates of malaria prevalence are also poor, and some researchers have suggested a direct link from malaria to poverty. This paper explores the potential impact of malaria on national income levels, using a dynamic general equilibrium framework with epidemiological features. We find that if there is no feasible prevention or control, malaria can have a significant impact on income levels. However, if people have any effective way of avoiding infection, the disease impacts on income levels are likely to be small. This is true even where preventive measures are costly.