Hello everyone,

In GAM-based logistic regression pseudo-absence data is necessary to fit the model with correspondent presence data. In many cases, pseudo-absence data are generated 10 times more than presence records in order to ensure sufficient landscape variety in the pseudo-absences. To ensure that the presences and pseudo-absences contributed equally to the model and avoid bias, I would like to know how that case-weighting option can be get with R. For example, I want weight each pseudo-absence as n/1000, where n is the number of presence sites and 1000 are pseudo-absences sites generated randomly.

Many thanks in advance,

Xavier Benito Granell
PhD student
IRTA- Ecosistemes Aquātics
Ctra. de Poblenou Km. 5,5
43540 Sant Carles de la Rāpita
(Tarragona) Spain
xavier.benito@irta.cat<mailto:xavier.benito@irta.cat>
www.irta.cat<http://www.irta.cat>


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