[R] help with polytomous logistic regression

[Anne]

Thank you, John! it is exactly what I need...looking forward to apply it

Anne

what would I become without this list?


----- Original Message ----- 
From: "John Fox" <jfox at mcmaster.ca>
To: "'Anne'" <anne.piotet at urbanet.ch>
Cc: "'R list'" <r-help at stat.math.ethz.ch>
Sent: Friday, January 07, 2005 3:56 PM
Subject: RE: [R] help with polytomous logistic regression


> Dear Anne,
>
> There's an anova() method for multinom objects that will allow you to get
> likelihood-ratio tests. Likewise, the Anova() function in the car package
> has a method for multinom objects.
>
> As to plotting, I have a paper, coauthored with Bob Andersen, on producing
> "effect" plots (partial plots) for polytomous logistic regression,
including
> multinomial and proportional-odds logistic regression. The paper, at
> <http://socserv.socsci.mcmaster.ca/jfox/logit-effect-displays.pdf>, has an
R
> function for computing such effects, including standard errors. There are
> examples in the paper as well. Eventually, I intend to incorporate this
into
> the effects package to make the graphs more or less automatic.
>
> Regards,
>  John
>
> --------------------------------
> John Fox
> Department of Sociology
> McMaster University
> Hamilton, Ontario
> Canada L8S 4M4
> 905-525-9140x23604
> http://socserv.mcmaster.ca/jfox
> -------------------------------- 
>
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch
> > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Anne
> > Sent: Friday, January 07, 2005 8:53 AM
> > To: R list
> > Subject: [R] help with polytomous logistic regression
> >
> > Hi!
> >
> > I'm trying to do some ploytomous logistic regression using
> > multinom() in the nnet package, but am a bit confused about
> > interpretation of the results Is it possible to get the
> > following quantities:
> >
> > I:  maximum likelihood estimates to test for fit of model and
> > significance of each predictor
> >
> > (I would like to produce a table of the following type)
> > Analysis of Variance: MLE    (values are non sensical, I know!)
> >                df      chi2           p
> > intercept   2       57            .003
> > v1            4       89            .876
> > v2            2         7            .05
> > LR        110     450            0.93
> >
> > II:  chi square values and corresponding p-values for each
> > level of the predictor variates (I'm OK for the estimates and
> > se from summary,)
> >
> >
> >                level estimate     se        chi2         p
> > intercept   1        5              .9         32          .002
> >                 2       6.3            .8         31          .03
> > v1             3       89            .876       43          .001
> >                 4       65            .05         67
> > 0.001
> >  v2...
> >
> >
> > Is there a convenient way to plot the results? (I'd like to
> > display visually the effects of the predictors: any sugestion?)
> >
> > OK, I probably miss something here (no experience with (non
> > ordinal) polytomous logistic regression yet!)
> >
> > Thank  very much to all
> >
> > Anne
> >
> > ----------------------------------------------------
> > Anne Piotet
> > Tel: +41 79 359 83 32 (mobile)
> > Email: anne.piotet at m-td.com
> > ---------------------------------------------------
> > M-TD Modelling and Technology Development PSE-C
> > CH-1015 Lausanne
> > Switzerland
> > Tel: +41 21 693 83 98
> > Fax: +41 21 646 41 33
> > --------------------------------------------------
> >
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> >
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