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Registros recuperados: 14 | |
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Olivia, Susan; Gibson, John; Smith, Aaron D.; Rozelle, Scott; Deng, Xiangzheng. |
Poverty maps provide information on the spatial distribution of welfare and can predict poverty levels for small geographic units like counties and townships. Typically regression methods are used to estimate coefficients from the detailed information in household surveys, which are then applied to the more extensive coverage of a census. One problem with standard regression techniques is that they do not take into account the ‗spatial dependencies‘ that often exist in the data. Ignoring spatial autocorrelation in the regression providing the coefficient estimates could lead to misleading predictions of poverty, and estimates of standard errors. Household survey data usually lack exact measures of location so it is not possible to fully account for this... |
Tipo: Conference Paper or Presentation |
Palavras-chave: China; Poverty; Small Area Estimation; Survey Methods; Spatial Models. |
Ano: 2009 |
URL: http://purl.umn.edu/47651 |
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Smith, Aaron D.; Morrison Paul, Catherine J.; Goe, W. Richard; Kenney, Martin. |
We use data from a 2001 survey of Great Plains farmers to explore the adoption, usage patterns, and perceived benefits of computers and the Internet. Our adoption results suggest that exposure to the technology through college, outside employment, friends, and family is ultimately more influential than farmer age and farm size. Notably, about half of those who use the Internet for farm-related business report zero economic benefits from it. Whether a farmer perceives that the Internet generates economic benefits depends primarily on how long the farmer has used the Internet for farm business and for what purposes. |
Tipo: Working or Discussion Paper |
Palavras-chave: Farm Management; Research and Development/Tech Change/Emerging Technologies. |
Ano: 2004 |
URL: http://purl.umn.edu/11947 |
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Smith, Aaron D.; Goe, W. Richard; Kemey, Martin; Morrison Paul, Catherine J.. |
This study uses data from a 2001 survey of Great Plains farmers to explore the adoption, usage patterns, and perceived benefits of computers and the Internet. Adoption results suggest that exposure to the technology through college, outside employment, friends, and family is ultimately more influential than farmer age and farm size. Notably, about half of those who use the Internet for farm-related business report zero economic benefits from it. Whether a farmer perceives that the Internet generates economic benefits depends primarily on how long the farmer has used the Internet for farm business and for what purposes. |
Tipo: Journal Article |
Palavras-chave: Agriculture; Competitiveness; Net benefits; Technology adoption; Research and Development/Tech Change/Emerging Technologies. |
Ano: 2004 |
URL: http://purl.umn.edu/30918 |
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Carter, Colin A.; Smith, Aaron D.. |
Genetic modification of crops has revolutionized food production, but it remains controversial due to food safety and environmental concerns. A recent food safety scare provides a natural experiment on the corn market's willingness to accept unapproved genetically modified organisms. In 2000, a genetically modified corn variety called StarLink was discovered in the food-corn supply, even though it was not approved for human consumption. To estimate the price impact of this event, we develop the relative price of a substitute method, which applies not only to the StarLink event but also to rare events in other markets. We apply this method to measure the price impact of the StarLink contamination on the U.S. corn market. We find that the contamination led... |
Tipo: Conference Paper or Presentation |
Palavras-chave: Food Consumption/Nutrition/Food Safety; Research and Development/Tech Change/Emerging Technologies; Q11; Q18; C22. |
Ano: 2006 |
URL: http://purl.umn.edu/25447 |
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Smith, Aaron D.. |
This article addresses the problem of forecasting time series that are subject to level shifts. Processes with level shifts possess a nonlinear dependence structure. Using the stochastic permanent breaks (STOPBREAK) model, I model this nonlinearity in a direct and flexible way that avoids imposing a discrete regime structure. I apply this model to the rate of price inflation in the United States, which I show is subject to level shifts. These shifts significantly affect the accuracy of out-of-sample forecasts, causing models that assume covariance stationarity to be substantially biased. Models that do not assume covariance stationarity, such as the random walk, are unbiased but lack precision in periods without shifts. I show that the STOPBREAK model... |
Tipo: Working or Discussion Paper |
Palavras-chave: Financial Economics; Research Methods/ Statistical Methods. |
Ano: 2004 |
URL: http://purl.umn.edu/11985 |
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Smith, Aaron D.. |
When applied to time series processes containing occasional level shifts, the logperiodogram (GPH) estimator often erroneously finds long memory. For a stationary short-memory process with a slowly varying level, I show that the GPH estimator is substantially biased, and I derive an approximation to this bias. The asymptotic bias lies on the (0,1) interval, and its exact value depends on the ratio of the expected number of level shifts to a user-defined bandwidth parameter. Using this result, I formulate the Modified GPH estimator, which has a markedly lower bias. I illustrate this new estimator via applications to soybean prices and stock market volatility. |
Tipo: Working or Discussion Paper |
Palavras-chave: Research Methods/ Statistical Methods. |
Ano: 2004 |
URL: http://purl.umn.edu/11974 |
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Smith, Aaron D.; Naik, Prasad A.; Tsai, Chih-Ling. |
In Markov-switching regression models, we use Kullback-Leibler (KL) divergence between the true and candidate models to select the number of states and variables simultaneously. In applying Akaike information criterion (AIC), which is an estimate of KL divergence, we find that AIC retains too many states and variables in the model. Hence, we derive a new information criterion, Markov switching criterion (MSC), which yields a marked improvement in state determination and variable selection because it imposes an appropriate penalty to mitigate the over-retention of states in the Markov chain. MSC performs well in Monte Carlo studies with single and multiple states, small and large samples, and low and high noise. Furthermore, it not only applies to... |
Tipo: Working or Discussion Paper |
Palavras-chave: Research Methods/ Statistical Methods. |
Ano: 2005 |
URL: http://purl.umn.edu/11976 |
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Smith, Aaron D.. |
In commodity futures markets, contracts with various delivery dates trade simultaneously. Applied researchers typically discard the majority of the data and form a single time series by choosing only one price observation per day. This strategy precludes a full understanding of these markets and can induce complicated nonlinear dynamics in the data. In this paper, I introduce the partially overlapping time series (POTS) model to model jointly all traded contracts. The POTS model incorporates time-to-delivery, storability, seasonality, and GARCH effects. I apply the POTS model to corn futures at the Chicago Board of Trade and the results uncover substantial inefficiency associated with delivery on corn futures. The results also support two theories of... |
Tipo: Working or Discussion Paper |
Palavras-chave: Marketing. |
Ano: 2004 |
URL: http://purl.umn.edu/11978 |
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Carter, Colin A.; Smith, Aaron D.. |
Genetic modification of crops has revolutionized food production, but it remains controversial due to food safety concerns. A recent food safety scare provides a natural experiment on the market's willingness to accept an increase in perceived risk from genetically modified (GM) food. We analyze the market impact of contamination of the U.S. food-corn supply by a GM variety called StarLink. We find that the contamination led to a 6.8 percent discount in corn prices and that the suppression of prices lasted for at least a year. |
Tipo: Working or Discussion Paper |
Palavras-chave: Food Consumption/Nutrition/Food Safety; Marketing. |
Ano: 2004 |
URL: http://purl.umn.edu/11997 |
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Registros recuperados: 14 | |
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