Analysis of Proportions of Affected Foetuses in Teratological Experiments

Abstract

This paper is concerned with the analysis of proportions affected when an increasing dose of a compound is applied to a group of laboratory animals. Several sets of data, including a set from a teratological experiment at the Shell Toxicology Laboratory, Sittingbourne, are analysed and some simulations are performed. Among the distributional models, the beta-binomial model is, in general, found to be the most sensitive to departures from the binomial. For testing the equality of two proportions, a comparison is made between the pseudo-t test, based on the jackknife method, and the likelihood ratio test, based on the beta-binomial model. From the limited comparison, no definite advantage of one approach over the other has been found; at the 5% level of significance both approaches lead to similar conclusions.

The generalized linear model and extensions: a review and some biological and environmental applications

“…For each combination of (φ, ρ) we generated data set from the beta-binomial distribution using the litter sizes given above. Further, simulations were run for the same values of φ and ρ, and the same probability distributions above using the fixed litter sizes of the low-dose group of Paul (1982) in which n = 19 and litter sizes r i = 5, 11, 7, 9, 12, 8, 6, 7, 6, 4, 6, 9, 6, 7, 5, 9, 1, 6, 9. Using 10 000 acceptable simulation runs based on the same criteria as that of Paul et al (2003) for rejection of data, we computed the mean bias and the MSE for each estimator.…”

Analysis of the Binary Littermate Data in the One‐Way Layout

“…Consider the data from Shell Toxicological Laboratory (Paul, 1982) given in Table 1. Pregnant females of Dutch rabbits are classified by the treatment dosage (control: C, low dose: L, medium dose: M, and high dose: H), and skeletal and visceral abnormalities of live fetuses are observed.…”

Statistical methods for the beta-binomial model in teratology.

“…This model has been used widely in the analysis of teratological data and has been studied by many biostatisticians (9,10 (12), and the theoretical aspect was discussed by Yamamoto and Yanagimoto (13).…”