just want to ask the following > > question: > > > probit<-glm(y1~x1+x2-1, > > family=binomial(link=probit)) > > Warning message: > > fitted probabilities numerically 0 or 1 occurred in: > > glm.fit(x = X, y = Y, > > weights = weights, start = start, etastart = > > etastart, > > why does that happen?