This paper came out recently - a guide to boosted regression trees for ecologists. Great potential for modelling species distributions from environmental data I think. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2656.2008.01390.x Well written (even I can understand it) and code for R is given with tutorials. Example for freshwater fish given. The method's non-linear. It doesn't produce nice smooth curves, but that seems to be it's strength as no prior assumptions are made about how the species should respond. I haven't tried it yet. Interested to hear what sort of results people get. Thomas Wilding Department of Biology Colorado State University Fort Collins Colorado 80523-1878 USA (+1 970) 491 2414
Boosted regression trees
2 messages · twilding, Sam Veloz
The code they provide is really easy to use and so far I have gotten great results. Does require a little of work though because you do have optimize several parameters, which they discuss in the paper. Also, because you are often running >1000 iterations, running each model takes much longer than a glm for example. So far with my work I have found better predictive accuracy using boosted regression trees vs GLM's or multi adaptive regression splines. Sam
twilding wrote:
This paper came out recently - a guide to boosted regression trees for ecologists. Great potential for modelling species distributions from environmental data I think. http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-2656.2008.01390.x Well written (even I can understand it) and code for R is given with tutorials. Example for freshwater fish given. The method's non-linear. It doesn't produce nice smooth curves, but that seems to be it's strength as no prior assumptions are made about how the species should respond. I haven't tried it yet. Interested to hear what sort of results people get. Thomas Wilding Department of Biology Colorado State University Fort Collins Colorado 80523-1878 USA (+1 970) 491 2414
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**************************************************** Sam Veloz Graduate Group in Ecology Department of Wildlife Fish and Conservation Biology UC Davis sdveloz at ucdavis.edu