[R] glm.nb, anova.negbin

juli g. pausas juli at ceam.es
Wed Sep 26 17:56:20 CEST 2001


> > I looked quickly, and it seems that this error comes actually from
> > `anova.glm'  and from the following `get':
> >
> >         if (!is.function(method))
> >             method <- get(method, mode = "function")
> >
> > `anova.negbin' sends the  `negbin' `object' to `anova.glm', but the
> > negbin object does not have a method (`glm' objects have method
> > "glm.fit"). There seem to be some other differences in `negbin' and
> > `glm' objects, so that `anova.glm' can't handle them (e.g., glm.control
> > object is missing in `negbin' object).
> >
> > I would like to help, but I don't have time now (got to mark exams).
>
> Yes, that's it: R is incompatible with S.  Although the information
> is in the saved call, R uses a duplicate copy.  In glm.nb() adding
>     fit$method <- method
>     fit$control <- control
> at the end seems to fix it, but without an example I can reproduce,
> I cannot of course be sure.
>

Thank you very much. This fix the problem on my own dataset.
I have tried to test in other reproducible exemples, following the example by
Ben Bolker (many thanks!), and it works well. I've only got problems when
trying to fit -1. I'm not sure if this is because it doen't make sense with
this dataset or because there is still a bug there (see below). Anyway, my
main problem is solved now. Many thanks.

t.tax <- rnbinom(200,mu=1,size=1)
t.var1 <- runif(200)
t.var2 <- runif(200)
t.var3 <- runif(200)
t.var4 <- runif(200)
t.var5 <- runif(200)

## ignore warning messages about convergence
t <- glm.nb(t.tax ~ t.var1)
t2 <- update(t, .~ .+t.var2)
t3 <- update(t2, .~ .+t.var3)
t4 <- update(t3, .~ .+t.var4)
t5 <- update(t4, .~ .+t.var5)
t6 <- update(t5, .~ . -1 )


anova(t, t2, t3, t4, t5, t6) ## OK
anova(t5)   ## OK
summary(t6) ## OK
anova(t6)   ## error

Error in "names<-.default"(*tmp*, value = c("", "", "", "", "", "", "",  :
        names attribute must be the same length as the vector
In addition: Warning message:
tests made without re-estimating theta in: anova.negbin(t6)




> And that was my main point: if reporting problems *please* report the
> results of traceback(), and if possible a small reproducible 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 272860 (secr)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595

--
Juli G. Pausas   (Mr)
Centro de Estudios Ambientales del Mediterraneo (CEAM)
C/ C.R. Darwin 14, Parc Tecnologic,
46980 Paterna, Valencia, SPAIN
Tel: (+ 34) 96 131 8227; Fax: (+ 34) 96 131 8190
mailto:juli at ceam.es
http://www.gva.es/ceam

GCTE Fire Network - http://www.gva.es/ceam/FireNetwork


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