seed.df <- read.table("seed.dat",header=T)
attach(seed.df)
seed.fit1 <- glm(cbind(y,n-y)~seed*root,binomial)
seed.fit2 <- glm(y/n~seed*root,binomial,weights=n)
seed.fit3 <- glm(y/n~seed*root,quasi(link="logit",variance="mu(1-mu)"),weights=n)
combo <- as.factor(c(rep("b75",5),rep("c75",6),rep("b73",5),rep("c73",5)))
seed.fit4 <- glm(y/n~combo-1,quasi(link="identity",variance="mu(1-mu)"),weights=n)