Don't use the names of R functions as variable names (was [R] what does this multinom (actually model.frame) error mean?)
Prof Brian Ripley
ripley at stats.ox.ac.uk
Thu Nov 13 08:26:40 CET 2003
Note that is a *model.frame* error, not a multinom one.
Don't use the names of R functions as variable names! I am sure that is
in the introductory documentation, and it is certainly stressed in my
books. Although I cannot be sure it seems very likely (perhaps because of
the scoping induced by namespaces) that your `rep' is being matched to the
function.
On Thu, 13 Nov 2003, Paul E. Johnson wrote:
> I have RedHat linux 9 with R 1.8.
>
> I'm estimating models with multinom with a dependent variable that has 3
> different values. Sometimes the models run fine and I can understand
> the results.
>
> Sometimes when I put in another variable, I see an indication that the
> estimation did work, but then I can't get the summary method to work.
> It's like this:
>
> > votemn1 <- multinom(vote~V023022+rep+V023027+ V023131,data=nes2002)
> # weights: 18 (10 variable)
> initial value 914.045424
> iter 10 value 474.831205
> iter 20 value 449.612637
> iter 20 value 449.612636
> iter 20 value 449.612636
> final value 449.612636
> converged
>
> > summary(votemn1)
> Error in model.frame(formula, rownames, variables, varnames, extras,
> extranames, :
> invalid variable type
>
> In this model, rep is a dichotomous (0,1) variable indicating if a
> person is a republican or not. If I drop that variable, the model does
> run and the summary method produces estimates & standard errors.
>
> > votemn2 <- multinom(vote~V023022+V023027+ V023131,data=nes2002)
> # weights: 15 (8 variable)
> initial value 917.341261
> iter 10 value 529.137064
> final value 527.178682
> converged
>
> > summary(votemn2)
> Call:
> multinom(formula = vote ~ V023022 + V023027 + V023131, data = nes2002)
>
> Coefficients:
> (Intercept) V023022 V023027 V023131
> 3 -2.2033403 0.9227144 -0.3835378 0.017960208
> 5 -0.8411559 -0.1853416 -0.2174085 0.005808468
>
> Std. Errors:
> (Intercept) V023022 V023027 V023131
> 3 0.5883961 0.07054401 0.0894393 0.05655965
> 5 1.2438595 0.14582161 0.1963035 0.12453307
>
> Residual Deviance: 1054.357
> AIC: 1070.357
> ...
>
>
--
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
More information about the R-help
mailing list