The data are from a teratological experiment comprised of two treatments. Sixteen pregnant female rats were fed a control diet during pregnancy and lactation, wheras an additional 16 were treated with a chemical agent. Each proportion represents the number of pups that survived the 21-day lactation period among those who were alive at 4 days. This is the binary version of Terat.Binomial.
Liang and Hanfelt, "On the Use of the Quasi-Likelihood Method in Teratological Experiments", Biometrics, September 1994. Original Data from: Weil, "Selection of the valid number of sampling units and a consideration of their combination in toxicological studies involving reproduction, teratogenisis or carcinogensis", Food and Cosmetics Toxicology, 1970.
gee(response~treatment, cluster=litter,family="binomial", link="logit", variance="glm.1", correlation=list(type="exchangeable"), data=Terat.Binary)