On Thu, 2009-06-18 at 13:23 -0600, Anke Konrad wrote: > Hi all, > > I am currently trying to compare different plant occurrence prediction > maps generated in R and exported into GRASS. One of these maps was > generated from a glm fitted to some data, and subsequently applying this > glm model to a wider region using predict.glm. The outcome here was a > probability of occurrence. The second map I generated using a gam > (mgcv), however, this map seems to have assigned something like a > negative log-likelihood of occurrence to each raster cell in the region. > Since I would like to compare the two, I would like to figure out a way > of having the same kind of output from the "predict" functions (either > probability OR negative log-likelihood). Does anyone know of a way of > changing the output options? And if not, does anyone have any > suggestions of how I could deal with this issue?
Did you set type = "response" in both predict.glm and predict.gam? It sounds like the gam predictions are still on the scale of the link function... G > > Thank you! > > ______________________________________________ > R-help@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. -- %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% Dr. Gavin Simpson [t] +44 (0)20 7679 0522 ECRC, UCL Geography, [f] +44 (0)20 7679 0565 Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ UK. WC1E 6BT. [w] http://www.freshwaters.org.uk %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%
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______________________________________________ R-help@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.
