A new class of modified binomial distributions with applications to certain toxicological experiments ?

A large class of distributions is proposed to fit the binary data obtained from certain toxicological experiments in which, for example, the outcome of interest is the occurrence of dead or malformed fetuses in a litter. This class of distribution includes the additive model proposed by Altham (1978) as a special case. The fits to three real-life data sets using this new distribution are shown to be much better than those provided by beta-binomial distribution used by Williams (1975) and by the correlated-binomial distribution proposed by Kupper and Haseman (1978).