Analysis of Dichotomous Response Data from Certain Toxicological Experiments

Abstract
In certain toxicological experiments with laboratory animals, littermate data are frequently encountered. One characteristic of this type of data is the litter effect, i.e., the tendency for animals from the same litter to respond more alike than animals from different litters. Attention is restricted to dichotomous response variables that frequently arise in toxicological studies, such as the occurrence of fetal death or a particular malformation. Various techniques for estimating the underlying probability of response are discussed. A number of generalized models that were recently proposed to take the litter effect into account are briefly reviewed and compared to the simpler binomial and Poisson models. Various procedures for assessing the significance of treatment-control differences are presented and their relative merits discussed. Future research needs in this area are outlined.