Sheng, Y;
Soto, J;
Orlu Gul, M;
Cortina-Borja, M;
Tuleu, C;
Standing, J;
(2016)
A New Generalized Poisson Mixture Model for Bimodal Count Data with Drug Effect: an application to Rodent Brief-Access Taste Aversion Experiments.
CPT: Pharmacometrics & Systems Pharmacology
, 5
(8)
pp. 427-436.
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Abstract
Pharmacodynamic count data can exhibit bimodality and non-equidispersion, complicating the inclusion of drug effect. The aim of this study was to explore four different mixture distribution models for bimodal count data by including both drug effect and distribution truncation. An example dataset, which exhibited bimodal pattern, was from rodent brief-access taste aversion (BATA) experiments to assess the bitterness of ascending concentrations of an aversive tasting drug. The two generalized Poisson mixture model performed the best and was flexible to explain both under and over dispersion. A sigmoid E max model with logistic transformation was introduced to link the drug effect to the data partition within each distribution. Predicted density-histogram plot is suggested as a model evaluation tool due to its capability to directly compare the model predicted density with the histogram from raw data. The modeling approach presented here could form a useful strategy for modeling similar count data types.
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