This paper concerns the impact of litter effects on the inference of dose- response relationships in teratological experiments with binary response. Kupper et al. (1986, Biometrics 42, 85-98) concluded that when intra-litter correlations are dose-dependent, the use of a common intra-litter correlation likelihood based on the beta-binomial distribution could lead to severe bias in estimation of the parameter β, which characterizes the dose-response relationship. We show here that the problems of bias and coverage probability for β could still be substantial when one uses the likelihood with heterogeneous intra-litter correlations. We then examine through a simulation study the performance of the quasi-likelihood method (Wedderburn, 1974, Biometrika 61, 439-447) and recommend that this method with a common intra- litter correlation parameter be used when the number of litters is small or modest.
ASJC Scopus subject areas
- Statistics and Probability
- Biochemistry, Genetics and Molecular Biology(all)
- Immunology and Microbiology(all)
- Agricultural and Biological Sciences(all)
- Applied Mathematics