The primary explanatory factor in the models studied so far was binary. Now we examine models with one binary and one multivalued ordered or unordered factor. For example, in a trial comparing surgery, a chemotherapy regimen and placebo, treatment is a three level nominal factor. But if the treatments are three doses of a drug, treatment is a three level ordinal factor. The specific aims of this chapter are:

• To present logit models for an unordered or ordered 2 × K table of counts from a product binomial design, and to derive the related exact conditional distributions.