A Methodological Note on a Stochastic Frontier Model for the Analysis of the Effects of Quality of Irrigation Water on Crop Yields

A stochastic frontier model is proposed for analysis of crop yields, which considers the effects of differing quality of irrigation water, in addition to different inputs and factors associated with technical inefficiency of production. The parameters of the production frontier involved are assumed to be a function of other variables, which measure the quality of the irrigation water.

An Investigation of Production Risk, Risk Preferences and Technical Efficiency: Evidence From Rainfed Lowland Rice Farms in the Philippines

Risk plays a vital role in farmers' decisions on input allocations and, therefore, output supply. This paper provides empirical evidence on the estimation of production risk, risk preferences and technical inefficiency. An eight-year panel data set is used for 46 rice farmers from a representative rainfed lowland environment in Central Luzon, Philippines. The heteroskedastic and stochastic frontier frameworks are reconciled and extended to accommodate the risk preferences of farmers in an analysis of production risk. Results show that technical inefficiency is overstated in risky production environments where farmers are risk-averse.production risk, risk preferences, technical efficiency, Productivity Analysis, Risk and Uncertainty,

Metafrontier Functions for the Study of Inter-regional Productivity Differences

The paper uses the concept of metafrontier functions to study regional differences in production technologies. The paper has three components. The first deals with the analytical framework necessary for the definition of metafrontier functions. The second component studies the properties of the metafrontier estimated using nonparametric data envelopment analysis (DEA). The third component focuses on the estimation of metafrontiers within the parametric framework of stochastic frontier analysis (SFA). The empirical application of the models uses cross-country agricultural sector data. The DEA and SFA metafrontiers are presented and discussed.

A study of technical inefficiencies of maize farmers within and outside the new agricultural extension program in the Harari region of Ethiopia

In 1994/95 Ethiopia launched a new agricultural intensification program based on the experience gained from the programs of the past and the success of the SG 2000 agricultural project in achieving higher yields in the subsistence sector. Stochastic frontier production functions were estimated for a sample of maize farmers within and outside the New Extension Program in order to study their technical inefficiencies and identify some of the factors contributing to variations in the productivity of maize farmers in the Harari Region of Ethiopia. It is found that there were technical change and changes in technical inefficiencies of maize farmers between 1994/95 and 1997/98. The average technical efficiency of maize farmers was 73 per cent and factors such as agricultural extension, formal education, and off-farm incomes were important factors affecting the technical inefficiencies of maize farmers within the program. We concluded that policies enhancing the managerial and decision-making capacity of maize growers contributed towards increasing their technical efficiencies and the objective of achieving increased maize production. Keywords: stochastic frontiers, technical inefficiencies, agricultural extension, Harari Region, Ethiopia South African Journal of Agricultural Extension Vol. 34(1) 2005: 136-15

Public subsidies, TFP and Efficiency: A tale of complex relationships

This paper evaluates the impact of subsidies on the different components of TFP for granted firms’ long-term growth. The impact of capital subsidies is captured by a quasi–experimental method (Multiple RDD), exploiting the conditions for a local random experiment created by an Italian industrial policy. Results show that capital subsidies negatively affect TFP growth in the short term, and signals of positive effects appear only after 3-4 years. This positive medium-long term impact comes especially through technological change and not through scale impact change, as may have been expected

Method of Moments Estimation of Usual Nutrient Intake Distributions

The parameters of the distribution of usual intakes of calcium, energy, iron, protein and vitamin C are estimated using four daily intakes of these dietary components for a sample of women selected in the Continuing Survey of Food Intakes by Individuals, conducted in 1985-86 by the Human Nutrition Information Service of the U.S. Department of Agriculture. The daily intakes for an individual are assumed to be the sum of the usual intake for that individual plus a measurement error. The variance and the third moment of the measurement errors for a given individual are assumed to be functions of the usual intake of that individual. For the five dietary components investigated, the standard deviation and cube root of the third moment of the measurement errors of an individual both appear to be linearly related to the usual intake for that individual. Moments of usual intake are estimated as functions of the sample moments of the four-day mean intakes and estimators for the parameters of the distribution of the measurement errors. Given estimates of the moments of usual intakes, the parameters of a particular distribution function can be estimated. The assumption that usual intakes of dietary components are distributed as Weibull random variables and that the measurement errors are generated as deviations of observations from the mean of Weibull distributions was accepted for all dietary components

Estimation of the Distribution of Usual Intakes for Selected Dietary Components

The U.S. Department of Agriculture (USDA) has been responsible for conducting periodic surveys to estimate food consumption patterns of households and/or individuals in the United States for over 50 years. Data from these surveys have had a significant impact on the formulation of food-assistance programs, on consumer education and on food regulatory activities. In recent years, there has been interest in estimating the proportion of the population that has insufficient intake or excessive intake of certain dietary components. Different approaches have been suggested for the estimation of this proportion. In all approaches, it is necessary to analyze data on dietary intakes for a sample of individuals. Also, all approaches recognize that an individual who has a low intake of a given dietary component on one day is not necessarily deficient (or at risk of being deficient) so far as that dietary component is concerned. It is low intake over a sufficiently long period of time that produces a dietary deficiency. A dietary deficiency exists when the usual (i.e., normal or long-run average) intake of the dietary component is less than the appropriate dietary standard

Analysis of crop-rotation experiments, with application to the Iowa Carrington-Clyde rotation-fertility experiments

This report presents a model by which several crop rotations are compared, and optimal fertilization and rotation practices determined. The model is developed with specific applicability to the rotation- fertility experiments at the Carrington-Clyde Experimental Farm near Independence, Iowa. The substitutability of legume meadow and chemical nitrogen fertilizer and the effect of carry-over of applied nitrogen from crop to crop are incorporated into the analysis. The split-plot nature of the rotation- fertility trials is noted, and a transformation of the yield data is employed to create nearly uncorrelated observations. Response functions are estimated for each crop in each rotation. Optimal fertilizer rates and rotations Eire determined on the basis of average annual return. Variance of return arising from yield variability over years is estimated. Continuous corn yielded the largest net income for the prices considered in the study. The net income per acre decreased with the introduction of oats and an increasing number of years of meadow. Variability of annual net return, however, was largest with continuous corn and decreased as the number of years of meadow in the rotations increased