Multicategory responses: proportional odds regression, model & estimate

See www.chrisbilder... for my book "Analysis of Categorical Data with R" and www.chrisbilder... for my course notes. This section discusses multicategory responses.
The video was created for STAT 875 at the University of Nebraska-Lincoln. The purpose of the course is to provide an introduction to categorical data analysis for statistics and non-statistics graduate students.

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What package should be used for proportional odds regression in retrospective research?