I have ordinal data (4 levels) which I have fit with:
a) 1 proportional-odds logistic regression model
b) 3 separate binary logistic regression models fit to values >= levels 2, 3, and 4.
The binary model curves and coefficients are 'very close' to those of the ordinal model, which has substantive implications. My question is whether there is a formal way to describe 'very close', other than looking at a plot of the curves and looking at the coefficients.