[Biomod-commits] Convergence problem with GLM

frank.breiner at wsl.ch frank.breiner at wsl.ch
Fri Jun 14 16:26:52 CEST 2013

Hi all,

when having only few presences and the ratio of the number of predictors 
to the number of presences is far from the recommanded 1/10 rule, GLM 
models often do not converge. This could result in binary predictions as 
shown in the attached figures.
How is the problem handled in Biomod? I think there is only a warning that 

the Model did not converge but the non-convergence models are also 
included in the ensemble. Correct?

As you can see from the figures the non-convergence GLM (top left) output 
fits with the predictions of GBM (top right) and Maxent.(bottom left). 
Bottom right is a self made Ensemble including also GLM.

For me it would make sense to include GLM output in the ensemble as the 
trend is the same. Does Biomod keep non-convergence models for the 
ensemble? What do you think? Keep it or remove it?

By the way: AUC values for the shown models suggest that GLM is not a bad 

GLM:            0.981
GBM:            0.998
MAXENT: 0.997
Ensemble:       0.998

Looking forward to your responses.


Frank Breiner
Eidg. Forschungsanstalt WSL
Biodiversität & Naturschutzbiologie
Zürcherstrasse 111
CH-8903 Birmensdorf

Tel.: +41 44 7392 418
Fax: +41 44 7392 215 

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