SABIIA - Sistema Aberto e Integrado de Informação em Agricultura (Sabiia)

Bogetoft, Peter.

We analyse how the aggregation of production processes affects efficiency evaluations. A production unit can be inefficient even though all its production processes are efficient. We show how to test if observed "inefficiencies" may be caused by an aggregation and how to correct efficiency measures for such aggregation generated inefficiencies. The tests and the adjusted efficiency measurement programs involve hypothetical dis-aggregations designed to put the evaluated unit in its best possible light.

AGGREGATION WITHOUT SEPARABILITY: TESTS OF U.S. AND MEXICAN AGRICULTURAL PRODUCTION DATA

Palavras-chave: Production Processes; Data Envelopment Analysis (DEA); Aggregation; Efficiency; Production Economics.

Ano: 1999

URL: http://purl.umn.edu/24190

Lin, Ni; Davis, George C.; Shumway, C. Richard.

The generalized composite commodity theorem (Lewbel 1996) is used to test for consistent aggregation of U.S. and Mexican agricultural production data in each of the categories for which earlier tests rejected homothetic separability. All U.S. agricultural outputs can be justifiably aggregated into as few as four categories. All Mexican agricultural outputs can be aggregated into as few as five categories. The aggregation of all outputs into a single output cannot be supported in either country by sufficient conditions provided by the generalized composite commodity theorem and/or a homothetically separable technology.

Investigating Distance Effects on Environmental Values: A Choice Modelling Approach

Palavras-chave: Aggregation; Separability; Generalized composite commodity theorem; Demand and Price Analysis.

Ano: 1998

URL: http://purl.umn.edu/20927

Concu, Giovanni B..

This paper describes a Choice Modelling experiment set up to investigate the relationship between distance and willingness to pay for environmental quality changes. The issue is important for the estimation and transfer of benefits. The Choice Modelling experiment allows testing distance effects on parameters of environmental attributes that imply different trade-offs between use and non-use values. The sampling procedure is designed to provide a "geographically balanced" sample. Several specifications of the distance covariate are compared and distance effects are shown to take complex shapes. Welfare analysis shows that disregarding distance produces under-estimation of individual and aggregated benefits and losses, seriously hindering the reliability of...

U.S. Demand for Food and Nutrition in the 20th Century

Palavras-chave: Aggregation; Choice Modelling; Distance; Geographical Sampling; Specification Tests; Environmental Economics and Policy; Q51; H4; D6..

Ano: 2006

URL: http://purl.umn.edu/25566

Beatty, Timothy K.M.; LaFrance, Jeffrey T..

A great deal of research on farm and food policy and consumer choice focuses on the link between food consumption and nutrition. This paper presents and applies a new method to analyze the demand for food and nutrients, and consumer welfare. The foundation for this method is the recent extension of the Gorman class of exactly aggregable demand models to incomplete demand systems. The purposes of this approach are to derive and implement coherent, flexible empirical models of food and nutrient demand, to estimate the model parameters consistently with aggregate data, and to make inferences on the impacts of farm and food policy changes on food and nutrient demand and consumer welfare of those policies. We apply this framework to annual per capita U.S....

AN ECONOMETRIC MODEL OF THE DEMAND FOR FOOD AND NUTRITION

Palavras-chave: Aggregation; Agricultural policy; Food demand; Gorman Systems of Demands; Nutrition; Demand and Price Analysis; Food Consumption/Nutrition/Food Safety.

Ano: 2005

URL: http://purl.umn.edu/25105

LaFrance, Jeffrey T..

A flexible, full rank two model of food consumption that is globally consistent with economic theory, aggregates across income, demographic variables, and variations in micro demand parameters, and accommodates tradeoffs between tastes and nutrition is derived. The econometric demand model is estimated with per capita U.S. consumption of 21 foods on the time period 1919-1994, excluding the World War II years 1942-1946. An approach for inferring the percentage of nutrients available from individual commodities in the U.S. food supply is derived and implemented empirically on the time period 1949-1995 for the nutrients energy, protein, total fat, carbohydrates, and cholesterol. The two sets of model results are combined to generate time paths for income...

The Measurement of the Energy Intensity of Manufacturing Industries: A Principal Components Analysis

Palavras-chave: Aggregation; Demand; Food; Nutrition; Hicksian Compensated Price Elasticities; Demand and Price Analysis; Food Consumption/Nutrition/Food Safety.

Ano: 1999

URL: http://purl.umn.edu/25004

Bernard, Jean-Thomas; Cote, Bruno.

Energy intensity is the ratio of energy use to output. Most industries deal with several energy sources and outputs. This leads to the usual difficulties of aggregating heterogeneous inputs and outputs. We apply principal components analysis to assess the information derived from six energy intensity indicators. We use two measures of total energy use (thermal and economic) and three measures of industry output (value added, value of production, and value of shipments). The data comes from manufacturing industries in Quebec, Ontario, Alberta, and British Columbia from 1976 to 1996. We find that the variation of the six energy intensity indicators that is accounted for by the first principal component is quite large. However, depending on how variables are...

Welfare Measurement and Representative Consumer Theory

Palavras-chave: Energy intensity; Aggregation; Principal components analysis; Resource /Energy Economics and Policy; Q40; C43; L60.

Ano: 2002

URL: http://purl.umn.edu/10544

Smith, V. Kerry; von Haefen, Roger H..

This paper generalizes results from Anderson, De Palma, and Thisse [1992] linking individual random utility and aggregate representative individual demand models, to consider a comparable relation for the willingness to pay functions for quality attributes of marketed goods. It also suggests how the logic can be used to describe links between choice occasion and aggregate models (across occasions) for an individual.

Palavras-chave: Willingness to pay; RUM; Aggregation; Consumer/Household Economics; DG1; Q2.

Ano: 1997

URL: http://purl.umn.edu/10646

Building Gorman's Nest

LaFrance, Jeffrey T.; Beatty, Timothy K.M.; Pope, Rulon D..

Gorman Engel curves are extended to incomplete systems. The roles of Slutsky symmetry and homogeneity/adding up are isolated in the rank and functional form restrictions for Gorman systems. Symmetry determines the rank condition. The maximum rank is three for incomplete and complete systems. Homogeneity/adding up determines the functional form restrictions in complete systems. There is no restriction on functional form in an incomplete system. Every full rank and minimal deficit reduced rank Gorman system has a representation as a polynomial in a single function of income. This generates a complete taxonomy of indirect preferences for Gorman systems. Using this taxonomy, we develop models of incomplete Gorman systems that nest rank and functional form and...

Is Storage at a Loss Merely an Illusion of Spatial Aggregation?

Palavras-chave: Aggregation; Functional form; Gorman Engel curves; Incomplete demand systems; Rank; Weak integrability; Demand and Price Analysis; D12; E21.

Ano: 2004

URL: http://purl.umn.edu/25027

Franken, Jason R.V.; Garcia, Philip; Irwin, Scott H..

The storage-at-a-loss paradox—stocks despite inadequate price growth to cover storage costs—is an unresolved issue of long-standing interest to economists. Alternative explanations include risk premiums for futures market speculators, convenience yields from holding stocks, and mismeasurement/aggregation of data. Statistical analyses of regional and elevator corn and soybean price growth in Illinois suggest limited aggregation effects and reveal a pattern of regional- and elevator-level backwardations in the presence of Illinois corn stocks that is inconsistent with aggregation explanations for storage at a loss. Interviews with elevator managers support the existence of convenience yields.

Tipo: Journal Article

Palavras-chave: Aggregation; Convenience yield; Corn; Intertemporal arbitrage; Regional and elevator data; Soybeans; Storage at a loss; Agribusiness; Marketing.

Ano: 2009

URL: http://purl.umn.edu/90658

Constant market shares analysis: uses, limitations and prospects

Ahmadi-Esfahani, Fredoun Z..

In this paper, we generalise the constant market shares (CMS) framework, with particular attention to the underlying theoretical conditions required for diagnostic interpretation. The approach is applied to the analysis of the export performance of the Australian processed food sector in South-East Asia over the period 1980–2003. We conclude that the usefulness of CMS analysis for evaluating a country’s international trade performance depends upon the empirical validity of the aggregation assumptions implicit in the diagnostic interpretation.

Tipo: Journal Article

Palavras-chave: Aggregation; Armington model; Competitiveness; Constant market shares; Marketing.

Ano: 2006

URL: http://purl.umn.edu/116983

On the Solutions to Full Rank Three Gorman Systems

LaFrance, Jeffrey T..

This letter closes a gap in the set of solutions for the full rank three systems of Gorman Engel curves and presents a unified expression for the indirect preferences in this case.

Using Weak Separability and Generalized Composite Commodity Theorem in Modeling Ground Beef Demand

Palavras-chave: Aggregation; Rank; Functional form; Integrability; Research Methods/ Statistical Methods; D12; E21.

Ano: 2005

URL: http://purl.umn.edu/25048

Schulz, Lee L.; Schroeder, Ted C.; Xia, Tian.

Replaced with revised version of paper 06/15/11.

TESTING AGGREGATION WITHOUT SEPARABILITY IN MEAT DEMAND: AN INVESTIGATION OF THE GENERALIZED COMPOSITE COMMODITY THEOREM

Palavras-chave: Aggregation; Generalized Composite Commodity Theorem; Beef demand; Weak separability; Demand and Price Analysis; Q13; Q18; R32.

Ano: 2011

URL: http://purl.umn.edu/103904

Davis, George C..

In the estimation of aggregate meat demand systems, weak separability is often a maintained assumption. However, only a few studies have tested and failed to reject this assumption. Recently, Lewbel (1996) developed a generalized composite commodity theorem (GCCT) that is less restrictive than weak separability. In this study, a data set in which the weak separability conditions for aggregation have been rejected is reconsidered to determine if aggregation can be based on the GCCT. Some subtleties of Lewbel's testing procedure that are not discussed by Lewbel are considered, and the fundamental problem of formulating aggregates prior to conducting tests for aggregation is addressed.

Data Aggregation and Vertical Price Transmission: An Experiment with German Food Prices

Palavras-chave: Aggregation; Demand; Weak separability; Generalized composite commodity theorem.; Demand and Price Analysis; Livestock Production/Industries.

Ano: 1998

URL: http://purl.umn.edu/20895

von Cramon-Taubadel, Stephan; Loy, Jens-Peter; Meyer, Jochen.

The impact of cross sectional aggregation over individual retail stores on the estimation and testing of vertical price transmission between the wholesale and retail levels is investigated using a unique data set of individual retail prices in Germany. Systematic differences between the results of estimations using aggregated data on the one hand, and disaggregated data on the other, are discussed theoretically and confirmed empirically. The results suggest that estimation with aggregated data generates misleading conclusions about price transmission behavior at the level of the individual units (i.e. retail stores) that underlie these aggregates.

Yield trend estimation in the presence of non-constant technological change and weather effects

Palavras-chave: Aggregation; Vertical Price Transmission; Food Prices; Germany; Demand and Price Analysis; Marketing; L11; D40.

Ano: 2006

URL: http://purl.umn.edu/25291

Conradt, Sarah; Bokusheva, Raushan; Finger, Robert; Kussaiynov, Talgat.

The application of yield time series in risk analysis prerequisites the estimation of technological trend which might be present in the data. In this paper, we show that in presence of highly volatile yield time series and non-constant technology, the consideration of the weather effect in the trend equation can seriously improve trend estimation results. We used ordinary least squares (OLS) and MM, a robust estimator. Our empirical analysis is based on weather data as well as farm-level and county-level yield data for a sample of grain-producing farms in Kazakhstan.

Tipo: Presentation

Palavras-chave: Yield detrending; Weather information; Robust trend estimation; Aggregation; Risk and Uncertainty; Q19.

Ano: 2012

URL: http://purl.umn.edu/122541

Unstable Individual Bids and Stable Market Demand

Alfnes, Frode; Rickertsen, Kyrre; Shogren, Jason F..

We explore preference stability at the individual and market level. We examine individual bidding behavior among 116 French consumers who participated in experimental auctions conducted seven months apart for five types of fish. We reject preference stability at the individual level, but not at the aggregate market level.

Aggregation and Calibration of Agricultural Sector Models Through Crop Mix Restrictions and Marginal Profit Adjustments

Palavras-chave: Aggregation; Consumer preferences; Demand; Experimental auctions; Food choice; Marketing; C91; D12; Q13.

Ano: 2011

URL: http://purl.umn.edu/114219

Wiborg, Torben; McCarl, Bruce A.; Rasmussen, Svend; Schneider, Uwe A..

All agricultural sector models must deal with aggregation and calibration somehow. The aggregation problem involves treating a group of producers as if they all responded in the same way as a single representative unit. The calibration problem concerns making a model reproduce as closely as possible an empirically observed set of decision maker actions. This paper shows how both calibration and aggregation are addressed through crop mix restrictions combined with marginal profit adjust-ments.

Aggregation Issues in the Estimation of Linear Programming Productivity Measures

Palavras-chave: Mathematical programming; Aggregation; Calibration; Crop mix; Marginal cost; Agricultural sector model; Agribusiness; C6; C61; Q1; Q11; Q17; Q18; R12; R13; R14.

Ano: 2005

URL: http://purl.umn.edu/24567

Shaik, Saleem; Mishra, Ashok K.; Atwood, Joseph A..

This paper demonstrates the sensitivity of the linear programming approach in the estimation of productivity measures in the primal framework using Malmquist productivity index and Malmquist total factor productivity index models. Specifically, the sensitivity of productivity measure to the number of constraints (level of dis-aggregation) and imposition of returns to scale constraints of linear programing is evaluated. Further, the shadow or dual values are recovered from the linear program and compared to the market prices used in the ideal Fisher index approach to illustrate sensitivity. Empirical application to U.S. state-level time series data from 1960-2004 reveal productivity change decreases with increases in the number of constraints. Further,...

Tipo: Report

Palavras-chave: Aggregation; Share-weights; Single and multiple output and input; Malmquist productivity index; Malmquist total factor productivity index; Agribusiness; Production Economics.

Ano: 2011

URL: http://purl.umn.edu/101783

TESTING AGGREGATION CONSISTENCY ACROSS GEOGRAPHY AND COMMODITIES

Liu, Qinghua; Shumway, C. Richard.

Consistent aggregation of production data across commodities and states was tested using Lewbel's generalized composite commodity theorem (GCCT). This was the first empirical GCCT test for consistent geographic aggregation and was applied to two groups of states. Consistent commodity aggregation was tested in all states for two output groups and three input groups and in one state for a larger number of groups. Using a more powerful test procedure than previously applied to production data, most tests for commodity aggregation gave ambiguous results. Consistent geographic aggregation was generally supported across Pacific Northwest states but was ambiguous across all Western states. Key words: Aggregation, commodity, geographic, composite commodity...

Unstable Individual Preferences and Stable Aggregate Demand: French Consumers’ Willingness to Pay for Farmed and Wild Cod

Palavras-chave: Aggregation; Commodity; Geographic; Composite commodity theorem; Multiple-comparison tests.; Research Methods/ Statistical Methods.

Ano: 2003

URL: http://purl.umn.edu/22201

Alfnes, Frode; Rickertsen, Kyrre.

We use panel data from two experiments conducted five months a part to investigate the stability of individual preferences and aggregate demand for five types of fish. Even though the bids in the two experiments are positively correlated, they clearly suggest that the individual preferences are unstable. This may be explained by internal desire for variety or by external effects such as new relevant information, seasonality in preferences, changes in the quality of the fish, and changes in the market price of fish. However, the aggregate demand curves of the participants are stable when we control for changes in the perceived quality of the fish and price expectations of the participants. In other words, the stability is generated by aggregation rather...