Dear List,
 
I am new to ROC analysis and the package ROCR. I want to compute the confidence intervals of sensitivity and specificity for a given cutoff value. I have used the following to calculate sensitivity and specificity:
 
data(ROCR.simple)
pred <- prediction(ROCR.simple$predictions, ROCR.simple$labels)
 
se.sp <- function (cutoff, performance) { 
    sens <- performance(pred,"sens") 
    spec <- performance(pred,"spec") 
    num.cutoff <- which.min(abs(sens@x.values[[1]] - cutoff))     
return(list(Cutoff=sens@x.values[[1]][num.cutoff], Sensitivity=sens@y.values[[1]][num.cutoff], Specificity=spec@y.values [[1]][num.cutoff])) 
} 
 
se.sp(cutoff=0.5, pred)

 
I would be grateful if someone could let me know how to get 95% CIs for these sensitivity and specificity?
 
Thanks vermuchch in advance.
Rasanga
 
 
 


      
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