
75Partial Models
constrained to vary by a common factor between the rst and second cutpoint equations. We
assume that φ
1
= 1 and φ
3
= 0 in order to identify the models. This only saves one parameter, but
it may be a useful constraint because the coefcients for Democrat and Independent display
very similar patterns in the unconstrained partial models. Thecoefcients are 65% weaker
in the second cutpoint equation in the logit model and 69% weaker in the probit model. The
results for the remaining variables are very similar to the unconstrained partial model results.
In order to further examine the substantive signicance of these relationsh