Public agricultural research has been conducted in Africa for decades. While many studies have examined its aggregate impacts, few have investigated how it affects the poor. This paper helps fill this gap by applying a new procedure to explore the ex post impacts of improved maize varieties on poverty in rural Ethiopia. Plot-level yield and cost changes due to adoption are first estimated using instrumental variable and marginal treatment effect techniques where possible heterogeneity is carefully accounted for. A backward derivation procedure is then developed to link treatment effect estimates with an economic surplus model to identify the counterfactual household income that would have existed without improved maize varieties. Poverty impacts are finally estimated by exploiting the differences between observed and counterfactual income distributions. Improved maize varieties have led to a 0.8-1.3 percentage drop of poverty headcount ratio and relative reductions of poverty depth and severity. However, poor producers benefit the least from adoption due to the smallness of their land holdings.JEL classifications: I32, O33, Q16, Q18

Regional scientists have long attempted to develop meaningful definitions and measures of economic diversity and diversification, and to establish functional relationships between diversity, diversification. and economic performance. The multiplicity of definitions and measures explains, in part, the confusion about these relationships. A framework that sorts out the overlaps, contradictions, and gaps of the various definitions and measures IS needed. Such a framework would explicitly address the question, "What is the relationship between a region's changing economic structure and performance?" In this paper it is suggested that an inputoutput model that incorporates elements of portfolio theory be used as the integrating framework for analysis.

Agricultural extension programs have changed significantly over the past four decades. What has changed and why? Have these changes affected adoption of innovations by farmers? What if anything should policy makers and extension agencies do differently, particularly in developing countries? Structural changes in agriculture, new types of agricultural technologies, tight public budgets, efforts to decentralize government, and emerging information and communication technologies (ICT) have led to pluralistic and, in some cases, lower‐cost extension and advisory services that combine public and private mechanisms for financing and implementing extension activities. Farmer groups and virtual networks play a growing role in technology diffusion, and extension services can exploit these networks using the latest ICT approaches.

Potato farmers in Ecuador rely on chemical inputs to manage pests and optimize yields. Integrated pest management techniques lower production costs, reduce pesticide exposure, and improve long-term agricultural sustainability. Public extension does not, however, exist in Ecuador, and cost-effective means of communicating complex messages to producers are needed. We analyze cost-effectiveness of alternative dissemination methods, including farmer field schools (FFS), field days, pamphlets, and word-of-mouth transmission. Field days and pamphlets have strong impacts on adoption, especially considering their low costs. FFS are effective, but expensive. Evidence also indicates significant diffusion from FFS to non-FFS farmers, indicating high complementarity across methods.

The adoption of more efficient farming practices and technologies that enhance agricultural productivity and improve environmental sustainability is instrumental for achieving economic growth, food security, and poverty alleviation in sub-Saharan Africa. Our research examines the interaction between public investments, community health, and adoption of productivity and land enhancing technologies by households in the northern Ethiopian state of Tigray. Agricultural technology adoption decisions are modeled as a sequential process where the timing of choices can matter. We find that time spent sick and opportunity costs of caring for sick family members are significant factors in adoption. Sickness, through its impact on household income and labor allocation decisions for healthcare and other activities, significantly reduces the likelihood of technology adoption. Our findings suggest that agencies working to improve agricultural productivity and land resource conservation should consider not only the financial status of potential adopters, but also their related health situation. Copyright 2004, Oxford University Press.