A client has classified geographical areas into groups. He has done this in various ways, based on substantive concerns, so there is a 2 group division, a 3 group division and so on. He has also measured various qualities of the areas. He wants to use the qualities to classify the areas into groups.
I tried multinomial logistic regression. For different cases, I got complete or quasicomplete separation, with the associated problems of non-existent maximum likelihood estimates, bizarre confidence limits for odds ratios and so on.
But, can I use that logistic regression as a classifier despite these problems?
If not, would a classification tree be better?