Richard, thanks,  I think it will work. I will calculate the cutoff value
and then, from the prediction object, find the fpr that is related to it and
put it as argument to performance. I will keep you informed.

Eleni

On Wed, Mar 19, 2008 at 11:51 AM, Richard Pearson <
richard.pearson@postgrad.manchester.ac.uk> wrote:

> Eleni
>
> Does the fpr.stop argument do what you want? This is described in
> ?performance under the details of the "auc" measure. Try, e.g.
>
> perform=performance(pred,measure="auc",fpr.stop=0.5)
>
>
> Richard.
>
>
> Eleni Christodoulou wrote:
> > Hello list,
> >
> > I am trying to perform ROC analysis and count the AUC in order to
> validate
> > my results. I use package ROCR. I would like to count the AUC not under
> the
> > cutoff found by "performance" but to use another cutoff that I
> calculate.
> > How could I change the following  command in order to get what I want?
> > perform=performance(pred,measure="auc",x.measure="cutoff"), where pred
> is a
> > prediction object.
> >
> > Thank you very much,
> > Eleni
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > 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.
> >
> >
>
> ______________________________________________
> 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.
>

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