Christian,
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?
a) look into the performance object, you find all values there
b) have a look at this thread
https://stat.ethz.ch/pipermail/r-help/attachments/20100523/51ec813f/attachment.pl
http://finzi.psych.upenn.edu/Rhelp10/2010-May/240021.html
http://finzi.psych.upenn.edu/Rhelp10/2010-May/240043.html
Claudia
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