R help - Oct 2010 - Fwd: HOW to use the survivalROC to get optimal cut-off values?

---------- Forwarded message ----------
From: Qian <qianguangyang@gmail.com>
Date: 2010/10/21
Subject: HOW to use the survivalROC to get optimal cut-off values?

Dear sir,
I am a student who want to use the time-dependent survivalROC
package.according to the,reference material,it only gives a set of ordered
cut-off values .eg.
-------------------------------------------------------------------------
data(mayo)
str(mayo)

attach(mayo)
ROC.1=survivalROC(Stime=time,status=censor,marker=mayoscore4,predict.time=365,lambda=0.05)
str(ROC.1)

plot(ROC.1$FP, ROC.1$TP, type="l", xlim=c(0,1), ylim=c(0,1),
  xlab=paste( "FP", "\n", "AUC =
",round(ROC.1$AUC,3)),
  ylab="TP",main="Mayoscore 4, Method = NNE \n  Year = 1")
  abline(0,1)


List of 6
 $ cut.values  : num [1:313] -Inf 4.58 4.9 4.93 4.93 ...           *only 5
values
* $ TP          : num [1:313] 1 0.999 0.999 0.999 0.998 ...
 $ FP          : num [1:313] 1 0.997 0.993 0.99 0.987 ...
 $ predict.time: num 365
 $ Survival    : num 0.93
 $ AUC         : num 0.888
----------------------------------------------------------------------------------------
so i dont know
how to use the survivalROC to get optimal cut-off values?(only 5 values)


Thank you very much!

YOURS SINCERELY

  GY QIAN
SHANGHAI,CHINA

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