My aim is to get an explanatory regression model for the following associations: 1) nominal variable (explanatory) --> ordinal outcome variable (outcome). 2) Numerical discrete (explanatory) --> ordinal outcome variable (outcome). I want to know which regression model to chose, which will fit with my data and accomplish the model's assumptions. Btw, I want to calculate for Prevalence Ratios (or IRR/RRR)

Thanks in advance.