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biomodhub / biomod2

BIOMOD is a computer platform for ensemble forecasting of species distributions, enabling the treatment of a range of methodological uncertainties in models and the examination of species-environment relationships.
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Habitat suitability, is there any unit ? #463

Closed lpittet92 closed 4 weeks ago

lpittet92 commented 1 month ago

Hello,

My question is very simple. Is there any unit to the suitability scale used for projection ?

I have been thinking of this for a while and couldn't find any answer.

Thank you for the great platform !

All the best,

Loic

MayaGueguen commented 1 month ago

Hello Loïc 👋

Predictions are by default rendered between 0 and 1000. Why ? Simply because it is lighter to save integer values rather than decimal values. And if you want to use several algorithms, with several pseudo-absence datasets, etc, number of models and then predictions quickly increase. So we multiply predictions by 1000 but there are still to be seen as probabilities 🙂

If this is too counter-intuitive for you, or if you don't have memory concerns, or you don't want to have to divide predictions by 1000, or simply you prefer it that way ! there is a parameter within BIOMOD_Projection and BIOMOD_EnsembleForecasting functions allowing to control for this : on_0_1000. It is set by default to TRUE and you can change it to FALSE to have directly predictions between 0 and 1.

Hope it helps, Maya