On the use of the quasi-likelihood method in teratological experiments.
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 beta, which characterizes the dose-response relationship. We show here that the problems of bias and coverage probability for beta 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.
Liang
K Y
KY
Department of Biostatistics, Johns Hopkins University, School of Hygiene and Public Health, Baltimore, Maryland 21205.
Hanfelt
J
J
D000704:Analysis of Variance; D000818:Animals; D004812:Epidemiologic Methods; D006801:Humans; D015233:Models, Statistical; D011336:Probability; D018600:Teratology / Q000379:methods*; D014116:Toxicology / Q000379:methods