[R] GAM hurdle models
Achim Zeileis
Achim.Zeileis at wu-wien.ac.at
Thu Jun 5 16:08:34 CEST 2008
On Thu, 5 Jun 2008, John Poulsen wrote:
> Hello,
>
> I have been using mgcv to run GAM hurdle models, analyzing presence/absence
> data with GAM logistic regressions, and then analyzing the data conditional
> on presence (e.g. without samples with no zeros) with GAMs with a negative
> binomial distribution.
>
> It occurs to me that using the negative binomial distribution on data with no
> zeros is not right, as the negative binomial allows zeros.
>
> Does anyone know of a package that does negative binomial GAM hurdle models?
> Or is there another quick fix to overcome this problem (e.g. using
> quasipoisson)?
Packages "VGAM" and "gamlss" both contain functionality for fitted
zero-inflated GAMs. If I recall correctly, both have ZIP and at least VGAM
also has ZINB as well as hurdle models for both distributions (under the
name "zero-altered" models).
I think that both require to use the same set of regressors in both parts
of the model. An implementation of zero-inflated models and hurdle models
without GAM effects but with separate sets of regressors is available in
"pscl".
Further information about the packages is available from:
http://www.stat.auckland.ac.nz/~yee/VGAM/
http://www.jstatsoft.org/v23/i07/
vignette("countreg", package = "pscl")
hth,
Z
> Thanks for your suggestions,
> John
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
More information about the R-help
mailing list