04 – Nominal Models

Categorical Data Analysis (Soc 681) · Purdue University · Fall 2026

The lecture notes for this section of the course, with the Stata and R code and output for every example. This site contains all the material and code for the course. If you prefer the slides in PDF format and/or the Stata replication do-file, these can be downloaded at: lecture slides · replication code.

Contents

• 4.0 Nominal DVs
• 4.1 Multinomial Logit Model
• 4.2 Predicted Probabilities
• 4.3 Marginal Effects
• 4.4 Example with 4 DV Categories
• 4.5 Conditional Odds Ratios (ORs)
• 4.6 Independence of Irrelevant Alternatives (IIA)
• 4.7 Review of Nominal DVs
• Appendix 4A: Combining Outcomes and Functional Forms
• Appendix 4B: Stata Code and Tips