[R] Library MASS -- polr function

Prof Brian Ripley ripley at stats.ox.ac.uk
Mon Feb 12 00:26:19 CET 2001

On Mon, 12 Feb 2001, Daniel Yearsley wrote:

> I seem to be able to extract everything but the t value and Std.error
> out of the summary function for polr.
> Category <- factor(rep(c(-1,0,1),2))
> Freq<-c(2,4,4,3,3,4)
> Sample<-factor(rep(c("x","y"), rep(3,2)))
> plr<-polr(Category~Sample,weights=Freq)
> coefficients(summary(plr))     ???

You do it exactly as for lm. The t-values are

summary(plr)$coefficients[, "t value"]

and the standard errors are

summary(plr)$coefficients[, "Std. Error"]

These work for me in your example. (R 1.2.1, MASS from VR_6.2-3)

You can also use


to get the estimated covaraince matrix of the estimates.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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