On generalized exponential transformations for proportions |
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Authors: | Waqas Ahmed Malik Hans-Peter Piepho |
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Institution: | 1. Biostatistics Unit, Institute of Crop Science, University of Hohenheim, Stuttgart, Germanyw.malik@uni-hohenheim.de;3. Biostatistics Unit, Institute of Crop Science, University of Hohenheim, Stuttgart, Germany |
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Abstract: | ABSTRACTTransformation of the response is a popular method to meet the usual assumptions of statistical methods based on linear models such as ANOVA and t-test. In this paper, we introduce new families of transformations for proportions or percentage data. Most of the transformations for proportions require 0 < x < 1 (where x denotes the proportion), which is often not the case in real data. The proposed families of transformations allow x = 0 and x = 1. We study the properties of the proposed transformations, as well as the performance in achieving normality and homoscedasticity. We analyze three real data sets to empirically show how the new transformation performs in meeting the usual assumptions. A simulation study is also performed to study the behavior of new families of transformations. |
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Keywords: | Binomial distribution Maximum likelihood estimation Mixed models Proportions Non normality Transformations |
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