[R] ROCR - best sensitivity/specificity tradeoff?

[Christian Meesters]

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 do I need an entirely different approach for this? Or is there an alternative solution?

Thanks,
Christian


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