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Registros recuperados: 22
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A SAMPLE SELECTION APPROACH TO CENSORED DEMAND SYSTEMS AgEcon
Yen, Steven T.; Lin, Biing-Hwan.
A censored demand system estimator is proposed by extending the sample selection model of Heckman. Censoring is governed by a selection mechanism which avoids the restricitve Tobit parameterization. Results of application to household consumption of beverages suggest the estimator produces slightly different elasticity estimates from the Tobit estimator. Demands for beverages are nearly unitary elastic, and net substitution is an obvious pattern.
Tipo: Conference Paper or Presentation Palavras-chave: Beverages; Censoring; Sample selection; Translog demand system; Demand and Price Analysis.
Ano: 2004 URL: http://purl.umn.edu/20082
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A Small-Sample Estimator for the Sample-Selection Model AgEcon
Golan, Amos; Moretti, Enrico; Perloff, Jeffrey M..
A semiparametric estimator for evaluating the parameters of data generated under a sample selection process is developed. This estimator is based on the generalized maximum entropy estimator and performs well for small and ill-posed samples. Theoretical and sampling comparisons with parametric and semiparametric estimators are given. This method and standard ones are applied to three small-sample empirical applications of the wage-participation model for female teenage heads of households, immigrants, and Native Americans.
Tipo: Working or Discussion Paper Palavras-chave: Maximum entropy; Sample selection; Monte Carlo experiments; Labor and Human Capital; Research Methods/ Statistical Methods.
Ano: 2001 URL: http://purl.umn.edu/25047
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Adoption of Site-Specific Information and Variable-Rate Technologies in Cotton Precision Farming AgEcon
Roberts, Roland K.; English, Burton C.; Larson, James A.; Cochran, Rebecca L.; Goodman, W. Robert; Larkin, Sherry L.; Marra, Michele C.; Martin, Steven W.; Shurley, W. Donald; Reeves, Jeanne M..
Probit analysis identified factors that influence the adoption of precision farming technologies by Southeastern cotton farmers. Younger, more educated farmer who operated larger farms and were optimistic about the future of precision farming were most likely to adopt site-specific information technology. The probability of adopting variable-rate input application technology was higher for younger farmers who operated larger farms, owned more of the land they farmed, were more informed about the costs and benefits of precision farming, and were optimistic about the future of precision farming. Computer use was not important, possibly because custom hiring shifts the burden of computer use to agribusiness firms.
Tipo: Journal Article Palavras-chave: Cotton; Grid soil sampling; Precision farming; Probit; Sample selection; Site-specific information; Technology adoption; Variable-rate application; D21; Q12; Q16.
Ano: 2004 URL: http://purl.umn.edu/42943
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Censored Probit Estimation with Correlation near the Boundary: A Useful Reparameteriztion AgEcon
Terza, Joseph V.; Tsai, Wei-Der.
The conventional computational algorithms for full information maximum likelihood (FIML) estimation of the censored probit model (see Farber, 1983), will sometimes fail to converge when the estimated value of the correlation coefficient (ñ) approaches ±1; even when the true value of ñ is not at a boundary. We show that a simple reparametrization of the censored probit model may afford straightforward Newton-Raphson convergence to the true FIML estimate for cases in which likelihood maximization under the conventional censored probit parameterization would have failed. Moreover, our method avoids the computational and inferential complications that arise in alternative methods that, based on a specified criterion, suggest fixing the estimated value of ñ at...
Tipo: Journal Article Palavras-chave: Sample selection; Endogenous treatment effects; Endogenous switching; Qualitative dependent variables; Informal elderly care; Research Methods/ Statistical Methods; I12; C24; C63.
Ano: 2006 URL: http://purl.umn.edu/50278
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CLIMATE CHANGE AND AGRICULTURAL PRODUCTIVITY IN SUB-SAHARAN AFRICA: A SPATIAL SAMPLE SELECTION MODEL AgEcon
Ward, Patrick S.; Florax, Raymond J.G.M.; Flores-Lagunes, Alfonso.
Using data at a high spatial resolution, we estimate a cereal yield response function conditional upon climatological and topographical features using a recently developed estimator for spatial process models when sample selection is of concern. We control for localized spatial correlation in unobserved disturbances affecting both the selection to plant cereals as well as in the resulting conditional yield response. We find that cereal yields across Sub-Saharan Africa will decline with increasing temperatures resulting from global climate change, and that failing to control for sample selection leads to underestimation of these adverse effects.
Tipo: Working or Discussion Paper Palavras-chave: Agricultural productivity; Climate change; Spatial econometrics; Sample selection; Generalized method of moments; Land Economics/Use; Productivity Analysis; Research Methods/ Statistical Methods; C31; Q18; C50.
Ano: 2011 URL: http://purl.umn.edu/116182
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Consumer Choice of Private Label or National Brand: The case of organic and non-organic milk AgEcon
Zhuang, Yan; Dimitri, Carolyn; Jaenicke, Edward C..
We use a two-stage, sample selection model to investigate organic milk purchases using Neilsen’s Homescan data. In the first stage, households decide on a weekly basis to buy mainly organic milk or non-organic milk. Results from this stage show that higher income, better education, having children at home, and several other demographic and marketing variables have a positive effect on organic choice. In the second stage, consumers then choose to buy mainly private label milk or national brand milk conditional on their first-stage choice. Most demographic and marketing variables are found to affect the organic and non-organic private label decision in the same way. However, our results show that a few factors, such as marriage status and children,...
Tipo: Conference Paper or Presentation Palavras-chave: Organic milk; Private label; Sample selection; Agribusiness; Consumer/Household Economics; Demand and Price Analysis.
Ano: 2009 URL: http://purl.umn.edu/49207
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Do Production Contracts Raise Farm Productivity? An Instrumental Variables Approach AgEcon
Key, Nigel D.; McBride, William D..
Estimating how the use of production contracts affects farm productivity is difficult when unobservable factors are correlated with both the decision to contract and productivity. To account for potential selection bias, this study uses the local availability of production contracts as an instrument for whether a farm uses a contract in order to estimate the impact of contract use on total factor productivity. Results indicate that use of a production contract is associated with a large increase in productivity for feeder-to-finish hog farms in the United States. The instrumental variable method makes it credible to assert that the observed association is a causal relationship rather than simply a correlation.
Tipo: Journal Article Palavras-chave: Productivity; Production contracts; Instrumental variables; Sample selection; Productivity Analysis.
Ano: 2008 URL: http://purl.umn.edu/45659
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Does Farm Size Really Converge? The Role of Unobserved Farm Efficiency AgEcon
Dolev, Yuval; Kimhi, Ayal.
We analyze the growth of family farms in Israeli cooperative villages between 1981 and 1995, using longitudinal data. We use instrumental variables to account for the endogeneity of initial farm size, and correct for selectivity due to farm survival. We also include a technical efficiency index, derived from the estimation of a stochastic frontier production model, as an explanatory variable. We find that technical efficiency is an important determinant of farm growth, and that not controlling for technical efficiency could seriously bias the results. The size distribution of Israeli family farms is found to be mostly diverging, while without technical efficiency farm growth seemed to be predominantly random.
Tipo: Working or Discussion Paper Palavras-chave: Farm size; Farm growth; Farm survival; Instrumental variables; Sample selection; Technical efficiency; Farm Management; Productivity Analysis; Q12; L25; C34.
Ano: 2008 URL: http://purl.umn.edu/45778
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Farmer Participation in Supermarket Channels, Production Technology, and Efficiency: The Case of Vegetables in Kenya AgEcon
Rao, Elizaphan J.O.; Brümmer, Bernhard; Qaim, Matin.
Supermarkets are gaining ground in the agri-food systems of many developing countries. While recent research has analyzed income effects in the small farm sector, impacts on productivity and efficiency have hardly been studied. We use a meta-frontier approach and combine this with propensity score matching to estimate treatment effects among vegetable farmers in Kenya. Participation in supermarket channels increases farm productivity in terms of meta-technology ratios by 45%. We also find positive and significant impacts on technical efficiency and scale efficiency. Supermarket expansion therefore presents opportunities for agricultural growth in the small farm sector, which is crucial for poverty reduction in Africa.
Tipo: Working or Discussion Paper Palavras-chave: Supermarkets; Technical efficiency; Scale efficiency; Meta-frontier; Meta-technology ratio; Sample selection; Kenya; International Development; Marketing; Production Economics; Productivity Analysis; D24; L23; O12; Q12; Q16.
Ano: 2011 URL: http://purl.umn.edu/113508
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Farmer Participation in Supermarket Channels, Production Technology and Technical Efficiency: The Case of Vegetables in Kenya AgEcon
Rao, Elizaphan J.O.; Brümmer, Bernhard; Qaim, Matin.
Supermarkets are currently gaining ground in the agri-food systems of many developing countries. While recent research has analyzed income effects in the small farm sector, impacts on farming efficiency have hardly been studied. Productivity effects in previous studies are also estimated with respect to different frontiers. Using a survey of Kenyan vegetable growers and a meta-frontier approach, we control for self-selection using propensity score matching and show that participation in supermarket channels increases farm productivity by 35-38%. Effects on technical efficiency are, however, insignificant. Supermarket expansion therefore presents opportunities for realizing agricultural growth, thus enhancing poverty alleviation and rural development.
Tipo: Conference Paper or Presentation Palavras-chave: Supermarkets; Meta-frontier; Productivity; Meta-technology ratio; Sample selection; Kenya; Agribusiness; Community/Rural/Urban Development; International Development; Production Economics; Productivity Analysis.
Ano: 2010 URL: http://purl.umn.edu/61190
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FIML estimation of an endogenous switching model for count data AgEcon
Miranda, Alfonso.
This paper presents code for fitting a FIML endogenous switching Poisson count model for cross-sectional data in Stata 7: the espoisson command. The Poisson process depends on an unobserved heterogeneity term, ε; a set of explanatory variables, x; and an endogenous dummy, d. The endogenous dummy depends on an unobserved random term, v. Correlation between ε and v is allowed. If a model with exogenous d is fitted instead, correlation between ε and v will result in simultaneous equation bias. The endogenous switching model corrects this problem. After describing the underlying econometric theory behind the command, an example is discussed.
Tipo: Journal Article Palavras-chave: Count models; Endogenous switch; Sample selection; Research Methods/ Statistical Methods.
Ano: 2004 URL: http://purl.umn.edu/116208
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Food Processors’ Use of Contracts to Purchase Agricultural Inputs: Evidence from a Pennsylvania Survey AgEcon
Jaenicke, Edward C.; Shields, Martin; Kelsey, Timothy W..
Using data from a survey of Pennsylvania food processors, we investigate what firm-level characteristics make a processor more or less likely to buy agricultural inputs and ingredients though contracts. We find that over 20 percent of Pennsylvania processors use contracts, and over 44 percent of agricultural inputs (based on value) are purchased under contract. We also analyze the two related questions of what firm attributes, attitudes, or other factors make a firm more likely to use contracts at all, and what factors lead a processor who does contract to use them more intensively.
Tipo: Journal Article Palavras-chave: Contracting; Food processors; Logit; Sample selection; Agribusiness; Agricultural Finance.
Ano: 2007 URL: http://purl.umn.edu/44698
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Maximum likelihood estimation of endogenous switching and sample selection models for binary, ordinal, and count variables AgEcon
Miranda, Alfonso; Rabe-Hesketh, Sophia.
Studying behavior in economics, sociology, and statistics often involves fitting models in which the response variable depends on a dummy variable—also known as a regime-switch variable—or in which the response variable is observed only if a particular selection condition is met. In either case, standard regression techniques deliver inconsistent estimators if unobserved factors that affect the response are correlated with unobserved factors that affect the switching or selection variable. Consistent estimators can be obtained by maximum likelihood estimation of a joint model of the outcome and switching or selection variable. This article describes a “wrapper” program, ssm, that calls gllamm (Rabe-Hesketh, Skrondal, and Pickles, GLLAMM Manual [University...
Tipo: Journal Article Palavras-chave: Endogenous switching; Sample selection; Binary variable; Count data; Ordinal variable; Probit; Poisson regression; Adaptive quadrature; Gllamm; Wrapper; Ssm; Research Methods/ Statistical Methods.
Ano: 2006 URL: http://purl.umn.edu/117582
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Modeling Willingness to Pay for Land Conservation Easements: Treatment of Zero and Protest Bids and Application and Policy Implications AgEcon
Cho, Seong-Hoon; Yen, Steven T.; Bowker, James Michael; Newman, David H..
This study compares an ordered probit model and a Tobit model with selection to take into account both true zero and protest zero bids while estimating the willingness to pay (WTP) for conservation easements in Macon County, NC. By comparing the two models, the ordered/unordered selection issue of the protest responses is analyzed to demonstrate how the treatment of protest responses can significantly influence WTP models. Both models consistently show that income and knowledge are positive and significant factors, while distance to poorer quality streams and duration of residency are negative and significant factors on WTP.
Tipo: Journal Article Palavras-chave: Censored dependent variable; Conservation easement; Protest bid; Sample selection; WTP; Agribusiness; Land Economics/Use; Political Economy; 25; 42; Q56.
Ano: 2008 URL: http://purl.umn.edu/45524
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On- and Off-Farm Labour Supply of Dutch Dairy Farmers: Estimation and Policy Simulations AgEcon
Ooms, Daan L.; Hall, Alastair R..
This research focuses on the effect of decoupled payments on labour supply of Dutch dairy farmers. Data availability leads to the fact that we can not estimate structural labour supply equations. We show how to derive reduced form equations suitable for policy simulations. We use the panel data sample selection estimation approach Wooldridge (1995) to estimate the off-farm labour supply equation. This method is based on Mundlak's (1978) linear panel data estimation approach, which we use to estimate the on-farm labour supply equations. Even though, simulations show a significant negative effect of decoupled payments on labour supply, the economic significance of this effect is very limited.
Tipo: Conference Paper or Presentation Palavras-chave: Decoupled payments; Labour supply; Panel data; Sample selection; Policy simulation; Labor and Human Capital; Livestock Production/Industries; C23; C24; C51; C53; D13; J22; Q12; Q18.
Ano: 2005 URL: http://purl.umn.edu/24506
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On Production Function Estimation with Selectivity and Risk Considerations AgEcon
Koundouri, Phoebe; Nauges, Celine.
In the estimation of production functions, ignoring risk considerations can cause inefficient estimates, while biased parameter estimates arise in the presence of sample selection. In the presence of uncertainty and selection bias, the latter introduced by the endogeneity of qualitative characteristics of inputs in crop choice, we show that correcting for risk considerations (a la Just and Pope, 1978, 1979) but not selection bias, can produce incorrect inferences in terms of risk behavior. The arguments raised in this study have estimation and policy implications for stochastic production analysis applied to all goods whose qualitative characteristics can affect sample selection.
Tipo: Journal Article Palavras-chave: Crop choice; Production risk; Sample selection; Production Economics.
Ano: 2005 URL: http://purl.umn.edu/30977
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PRODUCTION CONTRACTS AND FARM PRODUCTIVITY: EXAMINING THE LINK USING INSTRUMENTAL VARIABLES AgEcon
Key, Nigel D.; McBride, William D..
Estimating how production contracts affect farm productivity is difficult because the decision to use a contract is endogenous to other decisions affecting productivity. This study uses the local availability of production contracts as an instrument for whether a farm uses a contract in order to estimate the impact of contract use on total factor productivity. Results indicate that use of a production contract is associated with a large increase in productivity for feeder-to-finish hog farms in the U.S. The instrumental variable method makes it credible to assert that the observed association is a causal relationship rather than simply a correlation.
Tipo: Conference Paper or Presentation Palavras-chave: Productivity; Production contracts; Instrumental variables; Sample selection; Farm Management; Productivity Analysis.
Ano: 2007 URL: http://purl.umn.edu/9716
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Protest Adjustments in the Valuation of Watershed Restoration Using Payment Card Data AgEcon
Collins, Alan R.; Rosenberger, Randall S..
When using a willingness-to-pay (WTP) format in contingent valuation (CV) to value water-shed restoration, respondents may protest by questioning why they should pay to clean up a pollution problem that someone else created. Using a sample selection interval data model based on Bhat (1994) and Brox, Kumar, and Stollery (2003), we found that the decision to protest and WTP values were correlated. Protest sample selection bias resulted in a 300 percent overestimate of mean WTP per respondent. Using different ad hoc treatments of protesters, protest bias resulted in moderate effects (-10 percent to +14 percent) after controlling for sample selection bias.
Tipo: Journal Article Palavras-chave: Contingent valuation; Protest bias; Watershed restoration; Sample selection; Grouped Tobit; Resource /Energy Economics and Policy.
Ano: 2007 URL: http://purl.umn.edu/44706
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SEQUENTIAL ADOPTION OF SITE-SPECIFIC TECHNOLOGIES AND ITS IMPLICATIONS FOR NITROGEN PRODUCTIVITY: A DOUBLE SELECTIVITY MODEL AgEcon
Khanna, Madhu.
This paper analyzes the sequential decision to adopt two site-specific technologies, soil testing and variable rate technology (VRT), and their impact on nitrogen productivity in four Midwestern states. The results indicate that while farm location was a key variable influencing the adoption of soil testing, human capital and innovativeness of farmers had a significant impact on the adoption of VRT. A double selectivity model applied to correct for sample selection bias shows that gains in nitrogen productivity due to the two adoption decisions are largest for farms with below average soil quality and statistically insignificant for farms with above average soil quality. These findings have implications for the targeting of public policies designed to...
Tipo: Conference Paper or Presentation Palavras-chave: Site-specific crop management; Adoption; Bivariate probit; Sample selection; Crop Production/Industries; Research Methods/ Statistical Methods.
Ano: 1999 URL: http://purl.umn.edu/21599
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Sub-therapeutic Antibiotics and Impacts on U.S. Hog Farms AgEcon
McBride, William D.; Key, Nigel D.; Mathews, Kenneth H., Jr..
Antimicrobial drugs are fed to hogs at sub-therapeutic levels to prevent disease and promote growth. However, there is concern that the presence of antimicrobial drugs in hog feed is a factor promoting the development of antimicrobial drug-resistant bacteria. This study describes the extent to which antibiotics are used in hog production and how this changed between 2004 and 2009. This study also uses a sample-selection model to examine the impact that use has on the productivity of U.S. hog operations. Using hog producer data from 2004, the analysis did not find a relationship between productivity and sub-therapeutic antibiotics fed during finishing, but productivity was significantly improved when fed to nursery pigs. These results are being evaluated...
Tipo: Conference Paper or Presentation Palavras-chave: Antibiotics; Hogs; Sample selection; Farm Management; Production Economics.
Ano: 2011 URL: http://purl.umn.edu/103232
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