Dear Miltinho,

Since you don´t have absence, I think that you cannot calculate the AUC.
However, you can create pseudoabsences (by selecting areas from where you
know that the species is not present) at random and use them as surrogates
of absences data. This process has its drawbacks, which have been well
described in the scientific literature.

Hope it helps. Cheers,

Núria

2008/9/20 milton ruser <milton.ruser@gmail.com>

> Dear all,
>
>
>
> I have a probability of presence of distribution of a species of interest
>
> (varying from 0 to 1 in continuous form) and I have a set of points
>
> where I know that species really occurs. But I don´t have points of
> absence.
>
>
>
> So, for each true presence I know the estimated presence.
>
> I would like to know how can I compute AUC, taking account these
>
> Available data.
>
>
>
> Best wishes,
>
>
>
> Miltinho autronauta
>
> brazil
>
>        [[alternative HTML version deleted]]
>
>
> ______________________________________________
> 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.
>
>

	[[alternative HTML version deleted]]

