On Jun 18, 2009, at 3:23 PM, 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?
Have you actually read the help pages for predict.glm and
mgcv::predict.gam?
--
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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