R help - Dec 2010 - tests on polr object

Using ordered probit model, I get errors from dwt and bptest.

dwt:

Error in durbinWatsonTest.default(...) : requires vector of residuals

bptest:
Error in storage.mode(y) <- "double" :
  invalid to change the storage mode of a factor

I imagine I have to restate as an individual probit model for each category,
but is there an easier way?

thanks,
bp

	[[alternative HTML version deleted]]

Dear bp,

Is it sensible to do Durbin-Watson and Breusch-Pagan tests for
proportional-odds or ordered-logit models?

Best,
 John

--------------------------------
John Fox
Senator William McMaster 
  Professor of Social Statistics
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
web: socserv.mcmaster.ca/jfox

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at
r-project.org]
On
> Behalf Of Benjamin Polidore
> Sent: December-22-10 12:47 PM
> To: r-help at r-project.org
> Subject: [R] tests on polr object
> 
> Using ordered probit model, I get errors from dwt and bptest.
> 
> dwt:
> 
> Error in durbinWatsonTest.default(...) : requires vector of residuals
> 
> bptest:
> Error in storage.mode(y) <- "double" :
>   invalid to change the storage mode of a factor
> 
> I imagine I have to restate as an individual probit model for each
category,
> but is there an easier way?
> 
> thanks,
> bp
> 
> 	[[alternative HTML version deleted]]
> 
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