Manfred Zeller

Bio: Manfred Zeller is an academic researcher from University of Hohenheim. The author has contributed to research in topics: Poverty & Food security. The author has an hindex of 46, co-authored 259 publications receiving 9241 citations. Previous affiliations of Manfred Zeller include Agricultural & Applied Economics Association & University of Bonn.

Tradeoffs between income, biodiversity, and ecosystem functioning during tropical rainforest conversion and agroforestry intensification

Abstract: Losses of biodiversity and ecosystem functioning due to rainforest destruction and agricultural intensification are prime concerns for science and society alike. Potentially, ecosystems show nonlinear responses to land-use intensification that would open management options with limited ecological losses but satisfying economic gains. However, multidisciplinary studies to quantify ecological losses and socioeconomic tradeoffs under different management options are rare. Here, we evaluate opposing land use strategies in cacao agroforestry in Sulawesi, Indonesia, by using data on species richness of nine plant and animal taxa, six related ecosystem functions, and on socioeconomic drivers of agroforestry expansion. Expansion of cacao cultivation by 230% in the last two decades was triggered not only by economic market mechanisms, but also by rarely considered cultural factors. Transformation from near-primary forest to agroforestry had little effect on overall species richness, but reduced plant biomass and carbon storage by ≈75% and species richness of forest-using species by ≈60%. In contrast, increased land use intensity in cacao agroforestry, coupled with a reduction in shade tree cover from 80% to 40%, caused only minor quantitative changes in biodiversity and maintained high levels of ecosystem functioning while doubling farmers' net income. However, unshaded systems further increased income by ≈40%, implying that current economic incentives and cultural preferences for new intensification practices put shaded systems at risk. We conclude that low-shade agroforestry provides the best available compromise between economic forces and ecological needs. Certification schemes for shade-grown crops may provide a market-based mechanism to slow down current intensification trends.

Repayment performance in group-based credit programs in Bangladesh

Abstract: This paper analyzes the repayment rates of credit groups belonging to three group-based credit programs in Bangladesh: the Association for Social Advancement (ASA), the Bangladesh Rural Advancement Committee (BRAC), and the Rangpur Dinajpur Rural Service (RDRS). Hypotheses are drawn from economic theory relating group responsibility, and the resulting monitoring by peers, to a more effective enforcement of contractual obligations as well as to improved ability of the group as a whole to repay loans. Specific tests are performed on the following hypothesized determinants: group size, size of loans, degree of loan rationing, enterprise mix within groups, demographic characteristics, social ties and status, and occurrence of idiosyncratic shocks. Analysis is conducted using TOBIT maximum likelihood procedures. Implications for policy and institutional design are discussed.

Access to credit and its impact on welfare in Malawi

Abstract: Poor rural households in developing countries lack adequate access to credit. Many development professionals believe that this lack of credit has negative consequences for poor people's agricultural productivity, food security, health, and overall household welfare. Improved access to credit, they argue, will help poor rural households engage in more productive income-generating activities both on and off the farm and raise their living standards. Community and member-based microfinance programs have thus enjoyed considerable political and financial support during the 1990s. Yet in Access to Credit and Its Impact on Welfare in Malawi, Aliou Diagne and Manfred Zeller argue that access to microcredit may not be an effective way of alleviating poverty if the necessary infrastructure and socioeconomic environment are lacking.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

Abstract: We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

The microfinance promise

Abstract: In the past decade, microfinance programs have demonstrated that it is possible to lend to low-income households while maintaining high repayment rates--even without requiring collateral. The programs promise a revolution in approaches to alleviating poverty and spreading financial services, and millions of poor households are served globally. A growing body of economic theory demonstrates how new contractual forms offer a key to microfinance success--particularly the use of group-lending contracts with joint liability. For the most part, however, high repayment rates have not translated into profits, and studies of impacts on poverty yield a mixed picture. In describing emerging tensions, the paper highlights the diversity of innovative mechanisms beyond group-lending contracts, the measurement of financial sustainability, the estimation of economic and social impacts, the costs and benefits of subsidization, and the potential to reduce poverty through savings programs rather than just credit. The promise of microfinance has pushed far ahead of the evidence, and an agenda is put forward for addressing critical empirical gaps and sharpening the terms of policy discussion.

Precautionary Saving in the Small and in the Large

Abstract: The theory of precautionary saving is shown in this paper to be isomorphic to the Arrow-Pratt theory of risk aversion, making possible the application of a large body of knowledge about risk aversion to precautionary saving, and more generally, to the theory of optimal choice under risk In particular, a measure of the strength of precautionary saving motive analogous to the Arrow-Pratt measure of risk aversion is used to establish a number of new propositions about precautionary saving, and to give a new interpretation of the Oreze-Modigliani substitution effect