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Nonparallel Models
Nonparallel models are ordered regression models that relax the parallel regression
assumption for every independent variable in the model. The slopes for every variable
are allowed to freely vary across the binary cutpoint equations. Nonparallel models are
not ordinal models in the strictest sense because they do not impose constraints to main-
tain a strict stochastic ordering. However, ordinal patterns may emerge without the use
of the parallel constraints. The nonparallel cumulative and continuation ratio models are
ordinal in a weaker sense because reordering the outcome categories (e.g., 1,2,3,4 → 3,1,4,2)
affects the ...