Dear R heplper, I'm using polr: fm <- polr(factor(y) ~ x, ,method='logistic', data = dat, Hess=T) ans I'm getting a very strange message: Error in optim(start, fmin, gmin, method = "BFGS", hessian = Hess, ...) : initial value in 'vmmin' is not finite Can you help me? Thank you in advance, Grazia ---- M. Grazia Pittau, Ph.D. Post-Doctoral Research Fellow Department of Statistics Columbia University 1255 Amsterdam Avenue New York, NY 10027 grazia at stat.columbia.edu Phone: 212.851.2160 Fax: 212.851.2164