title: Clustered binary logistic regression in teratology data using a finite mixture distribution.
abstract: The beta-binomial distribution introduced by Skellam has been applied in many teratology problems for modelling the litter effect. Recently, Morel and Nagaraj proposed a new distribution for modelling cluster multinomial data when the clustering is believed to be caused by clumped sampling. It turns out that the distribution is a mixture of two binomial distributions and accommodates the estimation of an additional parameter to account for intra-litter effect. The new distribution arises from a cluster mechanism in which some individuals within a cluster exhibit the same behaviour while the remaining individuals from the cluster react independently of each other. Such a mechanism is a natural model in teratology problems, where typically a genetic trait is passed with a certain probability to the foetuses of the same litter. In this article, we use the new distribution to model binary responses with logistic regression. We analyse data from a teratology experiment to demonstrate that the new model provides a useful addition to current methodology. The experiment investigates the synergistic effect of the anticonvulsant phenytoin and trichloropopene oxide on the prenatal development of inbred mice. In a simulation study we investigate the type I error rate and the power of the maximum likelihood ratio test when the data follow a finite mixture distribution.
authors.affiliation: Procter & Gamble Company, Biostatistics & Medical Surveillance Department, Mason, Ohio 45040-9462, USA.
authors.forename: J G
authors.initials: JG
authors.lastname: Morel
authors.forename: N K
authors.initials: NK
authors.lastname: Neerchal
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000633:toxicity; D001846:Bone Development / Q000187:drug effects; D016000:Cluster Analysis; D003198:Computer Simulation; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000633:toxicity; D005260:Female; D016013:Likelihood Functions; D016015:Logistic Models; D051379:Mice; D008815:Mice, Inbred Strains; D016017:Odds Ratio; D010672:Phenytoin / Q000633:toxicity; D011247:Pregnancy; D018600:Teratology / Q000706:statistics & numerical data*; D014239:Trichloroepoxypropane / Q000633:toxicity
chemical_list: D000927:Anticonvulsants; D004791:Enzyme Inhibitors; D014239:Trichloroepoxypropane; D010672:Phenytoin