R help - May 2004 - Analysis of ordinal categorical data

Hi

I would like to analyse an ordinal categorical variable. I know how I can
analyse a nominal categorical variable (with multinom or if there are only two
levels with glm).

Does somebody know which command I need in R to analyse an ordinal categorical
variable?

I want to describe the variable y with the variables x1,x2,x3 and x4. So my
model looks like: y ~ x1+x2+x3+x4.

y: ordinal factor variable with levels (never, rare, bychance, often).

Thanks a lot in advance
Thomas

Dear Thomas,

One approach to an ordinal response variable is the proportional-odds model,
implemented in the MASS package as polr(). The proportional-odds assumption
may not hold, however.

I hope this helps,
 John 
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> thsudler at swissonline.ch
> Sent: Wednesday, May 05, 2004 7:45 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Analysis of ordinal categorical data
> 
> Hi
> 
> I would like to analyse an ordinal categorical variable. I 
> know how I can analyse a nominal categorical variable (with 
> multinom or if there are only two levels with glm).
> 
> Does somebody know which command I need in R to analyse an 
> ordinal categorical variable?
> 
> I want to describe the variable y with the variables x1,x2,x3 
> and x4. So my model looks like: y ~ x1+x2+x3+x4.
> 
> y: ordinal factor variable with levels (never, rare, bychance, often).
> 
> Thanks a lot in advance
> Thomas
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html

Thanks a lot for your advice. What do you mean with "the proportional-odds
assumption may not hold"? Does this solution with "polr" always
works? Or what's important to take into account?

Regards
Thomas
>Dear Thomas,
>
>One approach to an ordinal response variable is the proportional-odds model,
>implemented in the MASS package as polr(). The proportional-odds
>assumption
>may not hold, however.
>
>I hope this helps,
> John 
>
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch 
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of 
> thsudler at swissonline.ch
> Sent: Wednesday, May 05, 2004 7:45 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Analysis of ordinal categorical data
> 
> Hi
> 
> I would like to analyse an ordinal categorical variable. I 
> know how I can analyse a nominal categorical variable (with 
> multinom or if there are only two levels with glm).
> 
> Does somebody know which command I need in R to analyse an 
> ordinal categorical variable?
> 
> I want to describe the variable y with the variables x1,x2,x3 
> and x4. So my model looks like: y ~ x1+x2+x3+x4.
> 
> y: ordinal factor variable with levels (never, rare, bychance, often).
> 
> Thanks a lot in advance
> Thomas
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html

On Wed, 5 May 2004, John Fox wrote:
> One approach to an ordinal response variable is the proportional-odds
model,
> implemented in the MASS package as polr(). The proportional-odds assumption
> may not hold, however.
And you can find out by comparing the fit with a multinom fit -- see the 
MASS scripts for a worked example.

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

Thomas,
R code for Agresti's book "Catagorical Data Analysis  is available on  
Laura Thompson's
  web site.
http://math.cl.uh.edu/~thompsonla/
You might find the book and the code helpful.
Paul
On 5 May 2004, at 13:45, thsudler at swissonline.ch wrote:
> Hi
>
> I would like to analyse an ordinal categorical variable. I know how I 
> can analyse a nominal categorical variable (with multinom or if there 
> are only two levels with glm).
>
> Does somebody know which command I need in R to analyse an ordinal 
> categorical variable?
>
> I want to describe the variable y with the variables x1,x2,x3 and x4. 
> So my model looks like: y ~ x1+x2+x3+x4.
>
> y: ordinal factor variable with levels (never, rare, bychance, often).
>
> Thanks a lot in advance
> Thomas
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
>
>
P. B. Pynsent,
Research & Teaching Centre,
Royal Orthopaedic Hospital,
Northfield,
Birmingham, B31 2AP,
U. K.