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| Registros recuperados: 2.166 | |
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| Tannura, Michael A.; Irwin, Scott H.; Good, Darrel L.. |
| The purpose of this study was to investigate the relationship between weather, technology, and corn and soybean yields in the U.S. Corn Belt. Corn and soybean yields, monthly temperature, and monthly precipitation observations were collected over 1960 through 2006 for Illinois, Indiana, and Iowa. Multiple regression models were developed based on specifications found in studies by Thompson (1962 1963 1969 1970 1985 1986 1988). Estimated models explained at least 94% and 89% of the variation in corn and soybean yields for each state, respectively. Analysis of the regression results showed that corn yields were particularly affected by technology, the magnitude of precipitation during June and July, and the magnitude of temperatures during July and August.... |
| Tipo: Report |
Palavras-chave: Agricultural Finance; Financial Economics; Research Methods/ Statistical Methods. |
| Ano: 2008 |
URL: http://purl.umn.edu/37501 |
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| Lambert, Dayton M.; Lowenberg-DeBoer, James; Malzer, Gary L.. |
| Site-specific application of manure has the potential to improve crop production and environmental quality. If manure is applied where it is needed, in the quantity required by the crop, over application, with attendant runoff and leaching problems can be reduced. To implement this approach growers need site-specific crop response information. Increasing availability of site-specific yield information offers a way to estimate such crop responses. The objective of this study is to develop a methodology for estimating site-specific response of corn and soybeans to manure given soil test information, and to use that methodology to analyze an on-farm manure management trial conducted near Sleepy Eye, Minnesota. Both quantity and quality of the crop is... |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Research Methods/ Statistical Methods. |
| Ano: 2004 |
URL: http://purl.umn.edu/20091 |
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| Hamm, Lonnie; Brorsen, B. Wade. |
| Training a neural network is a difficult optimization problem because of numerous local minimums. Many global search algorithms have been used to train neural networks. However, local search algorithms are more efficient with computational resources, and therefore numerous random restarts with a local algorithm may be more effective than a global algorithm. This study uses Monte-Carlo simulations to determine the relative efficiency of a local search algorithm to 9 stochastic global algorithms. The computational requirements of the global algorithms are several times higher than the local algorithm and there is little gain in using the global algorithms to train neural networks. |
| Tipo: Conference Paper or Presentation |
Palavras-chave: Research Methods/ Statistical Methods. |
| Ano: 2002 |
URL: http://purl.umn.edu/36631 |
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| Cox, Nicholas J.. |
| The term spineplot has been applied over the last decade or so to a type of bar chart used particularly for showing frequencies, proportions, or percentages of two cross-classified categorical variables. The principle is that the areas of rectangular tiles are proportional to the frequencies in the cells of a contingency table. Often both coarse and fine structure are easy to see, including departures from independence. The main idea has, in fact, been rediscovered repeatedly over at least the last 130 years. In its most general form, it has been widely publicized under the name mosaic plots. This column introduces, discusses, and exemplifies a Stata implementation of spineplots. It is noted that a restriction to two variables is more apparent than real,... |
| Tipo: Article |
Palavras-chave: Spineplots; Mosaic plots; Bar charts; Graphics; Categorical data; Research Methods/ Statistical Methods. |
| Ano: 2008 |
URL: http://purl.umn.edu/120931 |
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| Johnston, Robert J.; Weaver, Thomas F.; Smith, Lynn A.; Swallow, Stephen K.. |
| Despite the many important uses (and potential abuses) of focus groups in survey design, the CV literature presents few guidelines to aid moderators in their interaction with focus group participants. This paper draws on the theory and practice of ethnographic interviewing to introduce general guidelines that can improve focus groups as an aid to CV research. The proposed guidelines illustrate types of questions that should reduce speculation and moderator-introduced bias in focus group responses, and improve the correspondence between focus group responses and actual behavior. The paper illustrates these ethnographic guidelines through a CV application concerning watershed resources. |
| Tipo: Journal Article |
Palavras-chave: Research Methods/ Statistical Methods. |
| Ano: 1995 |
URL: http://purl.umn.edu/31460 |
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| Registros recuperados: 2.166 | |
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