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Activity Number:
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134
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Type:
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Contributed
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Date/Time:
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Monday, August 4, 2008 : 10:30 AM to 12:20 PM
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Sponsor:
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Biometrics Section
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| Abstract - #301178 |
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Title:
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Testing for Group Effect in a 2 x k Heteroscedastic ANOVA Model
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Author(s):
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James F. Troendle*+
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Companies:
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National Institute of Child Health and Human Development
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Address:
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NIH, Bethesda, MD, 20892,
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Keywords:
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empirical likelihood ; likelihood ratio test ; power ; simulation
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Abstract:
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An approximate empirical likelihood ratio test (AELRT) is derived for the test of group main effect in a 2 x k heteroscedastic ANOVA model. To approximate the distribution of the test statistic under the null hypothesis, simulation from the approximate empirical maximum likelihood estimate (AEMLE) restricted by the null hypothesis is used. The homoscedastic ANOVA F-test and a Box-type approximation to the distribution of the heteroscedastic ANOVA F-test are compared to the AELRT in level and power. The AELRT procedure is shown by simulation to have appropriate type I error control (although possibly conservative) when the distribution of the test statistics are approximated by simulation from the constrained AEMLE. The methodology is motivated and illustrated by an analysis of folate levels in the blood among two alcohol intake groups while accounting for gender.
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