Quotation Maier, Marco. 2013. Dirichlet-Multinomial Regression Models in R. Psychoco 2013: International Workshop on Psychometric Computing, Zürich, Schweiz, 14.02-15.02..




Categorical data are ubiquitous in psychological research and commonly analyzed using, for example, multinomial logistic regression. The latter model, relying on the multinomial distribution, can exhibit serious problems related to over-dispersion. To remedy this, a compound distribution is constructed, where the multinomial distribution's parameters (probabilities in (0, 1) that must sum up to 1) are assumed to be Dirichlet-distributed. Integration over those probabilities yields a compound Dirichlet-multinomial distribution that has one parameter more than the multinomial distribution and acts like a "categorical Version" of the Dirichlet distribution with one parameter (α) per category. This additional parameter allows for a wide variety of possible distributional shapes (e.g., marginally U- or J-shaped, uniform, or unimodal). For dependent categorical variables that include n > 1 trials (at least for some observations), two regression models are described: one that models the alpha parameters directly and one with a reparametrization in means and precision, which can be interpreted similarly to multinomial logistic regression. This implementation extends the framework established in the R-package "DirichletReg".


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Publication's profile

Status of publication Published
Affiliation WU
Type of publication Paper presented at an academic conference or symposium
Language English
Title Dirichlet-Multinomial Regression Models in R
Event Psychoco 2013: International Workshop on Psychometric Computing
Year 2013
Date 14.02-15.02.
Country Switzerland
Location Zürich
URL http://eeecon.uibk.ac.at/psychoco/2013/


Maier, Marco (Former researcher)
Institute for Statistics and Mathematics IN (Details)
Research areas (ÖSTAT Classification 'Statistik Austria')
1105 Computer software (Details)
1162 Statistics (Details)
5509 Psychological methodology (Details)
5700 Applied statistics, social statistics (Details)
5701 Applied statistics (Details)
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