title: Estimating variance functions in developmental toxicity studies.
abstract: The presence of intralitter correlation is a well known issue for analysis of the developmental toxicology data. The intralitter correlation coefficients observed in developmental toxicology data are generally different across dose groups. In this paper we use a generalized estimating equation procedure to model jointly the mean parameters and the intralitter correlation coefficients as functions of dose levels. Our procedure is similar to that used by Prentice and Zhao (1991, Biometrics 47, 825-839) for estimating the mean and variance parameters.
authors.affiliation: Department of Mathematics, University of Mississippi, Oxford 38677, USA.
authors.forename: D
authors.initials: D
authors.lastname: Bowman
authors.forename: J J
authors.initials: JJ
authors.lastname: Chen
authors.forename: E O
authors.initials: EO
authors.lastname: George
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000008:administration & dosage / Q000633:toxicity; D000014:Abnormalities, Drug-Induced; D000704:Analysis of Variance; D000818:Animals; D001699:Biometry / Q000379:methods*; D002972:Cleft Palate / Q000139:chemically induced; D064420:Drug-Related Side Effects and Adverse Reactions; D005314:Embryonic and Fetal Development / Q000187:drug effects; D005260:Female; D005313:Fetal Death / Q000139:chemically induced; D008098:Litter Size; D051379:Mice; D011247:Pregnancy; D013723:Teratogens / Q000633:toxicity*
chemical_list: D013723:Teratogens; D015085:2,4,5-Trichlorophenoxyacetic Acid