Dear list
 
I have 5 markers that can be used to detect an infection in combination. Could you please advise me how to use functions in ROCR/ other package to produce the ROC curve for a combination of markers?
 
I have used the following to get ROC statistics for each marker.
pred <- prediction(y$marker1, y$infectn)
perf <-performance(pred,"tpr","fpr")
plot(perf,ave="threshold",spread.estimate="boxplot")

But I want know whether we could get this for more than one marker, so we can look at how good the markers in combination to predict the infection. I'm very grateful for any suggestion/help.
 
Thanks
Rasanga
 

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