Re: [R] ROCR - best sensitivity/specificity tradeoff?

From: David Winsemius <dwinsemius_at_comcast.net>
Date: Wed, 06 Apr 2011 17:03:39 -0400

On Apr 6, 2011, at 2:27 PM, Christian Meesters wrote:

> Hi,
>
> My questions concerns the ROCR package and I hope somebody here on
> the list can help - or point me to some better place.
>
> When evaluating a model's performane, like this:
>
>
> pred1 <- predict(model, ..., type="response")
> pred2 <- prediction(pred1, binary_classifier_vector)
> perf <- performance(pred, "sens", "spec")
>
> (Where "prediction" and "performance" are ROCR-functions.)
>
> How can I then retrieve the cutoff value for the sensitivity/
> specificity tradeoff with regard to the data in the model (e.g.
> model = glm(binary_classifier_vector ~ data, family="binomial",
> data=some_dataset)? Perhaps I missed something in the manual?

Or perhaps in your learning phase regarding decision theory perhaps? You have not indicated that you understand the need to assign a cost to errors of either type before you can talk about a preferred cutoff value.

> Or do I need an entirely different approach for this? Or is there an
> alternative solution?
>
> Thanks,
> Christian

-- 

David Winsemius, MD
West Hartford, CT

______________________________________________
R-help_at_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.
Received on Wed 06 Apr 2011 - 21:08:22 GMT

Archive maintained by Robert King, hosted by the discipline of statistics at the University of Newcastle, Australia.
Archive generated by hypermail 2.2.0, at Wed 06 Apr 2011 - 21:20:28 GMT.

Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help. Please read the posting guide before posting to the list.

list of date sections of archive