Abstract Details
Activity Number:
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684
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Type:
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Contributed
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Date/Time:
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Thursday, August 8, 2013 : 10:30 AM to 12:20 PM
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Sponsor:
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Biometrics Section
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Abstract - #308746 |
Title:
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Two Group Comparisons Using Mean-Based Tests Derived from Zero-Inflated Gamma and Zero-Inflated Log-Normal Models
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Author(s):
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Elizabeth Mills*+ and Jeffrey D. Dawson
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Companies:
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Univerisity of Iowa and The University of Iowa
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Keywords:
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semicontinuous data ;
point-mass mixture data ;
consonant tests ;
two-part models ;
regression
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Abstract:
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Positive continuous data with a point-mass at zero can be modeled via two-part models assuming distributions such as zero-inflated gamma and zero-inflated log-normal. The two parts model the probability of a nonzero outcome and the distribution of the nonzero outcomes. Many researchers have used these models making conclusions based on the two parts separately. This presentation explores methods of combining the two parts of these models. Specifically, tests are derived to compare the overall means of two groups using the difference of the overall group means and the ratio of group means. Simulation studies are used to explore the Type 1 error and power both when the models are correctly specified and when they are misspecified. The use of these mean-based tests will also be illustrated through data obtained through our collaboration work in the field of neurology.
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Authors who are presenting talks have a * after their name.
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