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Activity Number:
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162
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Type:
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Contributed
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Date/Time:
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Monday, August 3, 2009 : 10:30 AM to 12:20 PM
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Sponsor:
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Biometrics Section
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| Abstract - #303454 |
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Title:
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Optimal Experimental Designs for Determining Optimal Levels of Fertilizer
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Author(s):
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Wade Brorsen*+ and Francisca G.C. Richter
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Companies:
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Oklahoma State University and Federal Reserve Bank of Cleveland
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Address:
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, Stillwater, OK, 74078-6026,
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Keywords:
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c-optimality ; experimental design ; mixed models ; random effects ; agriculture ; production function
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Abstract:
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The question addressed is what experimental design to use to get a minimum variance estimate of the expected profit maximizing level of nitrogen fertilizer? A general analytical solution could not be obtained, so the problem is investigated numerically for a specific example. Mixed effects models for winter wheat (Triticum aestivium L.) yield are estimated for both Mitscherlich and linear plateau functions. With three design points, one should be at a high level and one should be low. The choice of the middle design point makes little difference over a wide range of values. The optimal middle design point is lower for the Mitscherlich functional form than it is for the plateau function. Equally spaced designs with more design points have a precision close to the three-point designs. The loss from using a nonoptimal experimental design is small.
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