The impact of uncertainty in a class of objective functions

This note analyzes some properties of a class of models involving optimization under uncertainty. Such models are characterized by a specific form of the objective function which is frequently encountered by economists. The discussion presented below generalizes a method which has been applied by several theoreticians [1–4, 8] to the analysis of specific topics in the theory of the firm and the problem of investment under uncertainty. This method makes use of a specific parameterization of risk and imposes some restrictions on decision makers' behavior, thus implying a model not as general as the one presented by Rothschild and Stiglitz [6, 7]. However, the present model is still plausible and affords some definite results where more general models are ambiguous.     

Agricultural Extension: Good Intentions and Hard Realities

What considerations lead policymakers to invest in agriculturalextension as a key public responsibility, and what factors andagency incentives explain differences in extension system performance?To help answer these questions, this article provides a frameworkoutlining farmers' demand for information, the public goodscharacter of extension services, and the organizational andpolitical attributes affecting the performance of extensionsystems. This conceptual framework is used to analyze severalextension modalities and their likely and actual effectiveness.The analysis highlights the efficiency gains that can come fromlocally decentralized delivery systems with incentive structuresbased on largely private provision, although in most poorercountries extension services will remain publicly funded.      

Land Tenure and Property Rights: Theory and Implications for Development Policy

This article explores the nature of property rights systems,their evolution, and their effect on resource allocation. Itis argued that certain institutional arrangements for land rightshave evolved in order to reduce uncertainty and increase efficiencyin credit as well as in land markets. Of particular relevanceto developing countries, the article emphasizes the contributionof public sector infrastructure to effective land rights systems.An appendix to the article presents a formal model analyzingthe effects of security of land rights on land prices, the intensityof cultivation, and the use of credit. Empirical evidence fromThailand supports several of the propositions derived from themodel.     

Risk and return: The case of merging firms

This study examines the market for acquisitions and the impact of mergers on the returns to the stockholders of the constituent firms. While employing the two-factor market model as recently developed and applied by Black-Jensen-Scholes and Fama-MacBeth, this study also considers changes in risk in analyzing the impact of mergers on stock prices. The results of the study are consistent with the hypothesis that the market for acquisitions is perfectly competitive and with the hypothesis that information regarding mergers is efficiently incorporated in the stock prices. Stockholders of acquiring firms seem to earn normal returns from mergers as from other investment-production activities with commensurate risk levels. Stockholders of acquired firms earn abnormal returns of approximately 14%, on the average, in the seven months preceding the merger.     

Cost-Effectiveness of Alternative Integrated Pest Management Extension Methods: An Example from Bangladesh

This study examines the cost-effectiveness of alternative methods for diffusing integrated pest management practices in Bangladesh. Methods compared include farmer field schools, field days, and extension agent visits. Farmer field school participants were more likely to adopt integrated pest management practices than recipients of messages from field days and agent visits. However, due to lower costs per participant, field days were the most cost-effective means for stimulating adoption of simpler practices and extension agent visits were the most cost-effective for extending more complex practices.     

Sending Farmers Back to School: The Impact of Farmer Field Schools in Indonesia

This paper evaluates the impact of farmer field schools, an intensive participatory training program emphasizing integrated pest management. The evaluation focuses on whether program participation has improved yields and reduced pesticide use among graduates and their neighbors who may have gained knowledge from graduates through informal communications. The study utilizes panel data covering 1991–99 in Indonesia. The analysis, employing a modified "difference-in-differences" model, indicates that the program did not have significant impacts on the performance of graduates and their neighbors. Several plausible explanations for this outcome are discussed, and recommendations for improvements are suggested.     

Time Series Analysis of Repeated Surveys: The State–space Approach

Cross sectional estimates from repeated surveys form a time series { y_t }. These estimates can be viewed as the sum y _t = Y _t + e _t of two processes, { Y _t }, the population process and { e _t }, the survey error process. Serial correlations in the latter series are usually present, mainly due to sample overlap. Other sources of data such as censuses, administrative records and demographic population counts are also available. The state–space modelling approach to the analysis of repeated surveys allows combining information from different sources, incorporating benchmarking constraints in a natural way. Results from these methods seem to compare favourably with those from X-11-ARIMA in filtering out survey errors.