65Partial Models
The values for the cutpoints (τ
m
) and the coefcients for the second set of independent
variables (η
m
) vary across equations, whereas the values for the independent variables
(xand ω) and the coefcients for the rst set of variables (β) remain constant across equa-
tions. This partial model is unconstrained in the sense that the values for η
m
freely vary
across cutpoint equations. In the constrained partial model, these coefcients vary by one
or more common factors across equations.
3.3.2 Constrained Partial Continuation Ratio Models
The constrained partial continuation ratio model is a nonlinear conditional probability
model that relaxes the parallel regression assumption for two subsets of independent vari-
ables in the model. ...