Message-ID: <49A4832B.1040904@yorku.ca>
Date: 2009-02-24T23:30:51Z
From: Michael Friendly
Subject: polr (MASS): score test for proportional odds model
For the following model,
library(vcd)
arth.polr <- polr(Improved ~ Sex + Treatment + Age, data=Arthritis)
summary(arth.polr)
where Improved is an ordered, 3-level response I'm looking for a
*simple* way to test
the validity of the proportional odds assumption, typically done via a
score test
for equal slopes/effects over the predictors.
I do find a po.test= option in the repolr package for repeated measures,
but for my
(tutorial) purposes this is too complex. Did I miss something simpler?
--
Michael Friendly Email: friendly AT yorku DOT ca
Professor, Psychology Dept.
York University Voice: 416 736-5115 x66249 Fax: 416 736-5814
4700 Keele Street http://www.math.yorku.ca/SCS/friendly.html
Toronto, ONT M3J 1P3 CANADA