The proportional odds (PO) assumption for ordinal regression analysis is often violated because it is strongly affected by sample size and the number of covariate patterns. To address this issue, the partial proportional odds (PPO) model and the generalized ordinal logit model were developed. However, these models are not typically used in research. One likely reason for this is the restriction of current statistical software packages: SPSS cannot perform the generalized ordinal logit model analysis and SAS requires data restructuring. This article illustrates the use of generalized ordinal logistic regression models to predict mathematics proficiency levels using Stata and compares the results from fitting PO models and generalized ordinal logistic regression models.
Liu, Xing and Koirala, Hari
"Ordinal Regression Analysis: Using Generalized Ordinal Logistic Regression Models to Estimate Educational Data,"
Journal of Modern Applied Statistical Methods:
1, Article 21.
Available at: http://digitalcommons.wayne.edu/jmasm/vol11/iss1/21