[R] area under roc curve

2011-04-14 Thread agent dunham
Dear all, 


I want to measure the goodness of prediction of my linear model. That's why
I was thinking about the area under roc curve. 

I'm trying the following, but I don't know how to avoid the error. Any help
would be appreciated. 

library(ROCR) 

model.lm - lm(log(outcome)~log(v1)+log(v2)+factor1)
pred-predict(model.lm)
pred-prediction(as.numeric(pred), as.numeric(log(outcome)))
auc-performance(pred,auc)

Error en prediction(as.numeric(pred), as.numeric(log(outcome))) : 
  Number of classes is not equal to 2.
ROCR currently supports only evaluation of binary classification tasks.
u...@host.com

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Re: [R] area under roc curve

2011-04-13 Thread Frank Harrell
ROC area does not measure goodness of prediction but does measure pure
predictive discrimination.  The generalization of the ROC area is the
C-index for continuous or censored Y.  See for example the rcorr.cens
function in the Hmisc package.
Frank

agent dunham wrote:
 
 Dear all, 
 
 
 I want to measure the goodness of prediction of my linear model. That's
 why I was thinking about the area under roc curve. 
 
 I'm trying the following, but I don't know how to avoid the error. Any
 help would be appreciated. 
 
 library(ROCR) 
 
 model.lm - lm(log(outcome)~log(v1)+log(v2)+factor1)
 pred-predict(model.lm)
 pred-prediction(as.numeric(pred), as.numeric(log(outcome)))
 auc-performance(pred,auc)
 
 Error en prediction(as.numeric(pred), as.numeric(log(outcome))) : 
   Number of classes is not equal to 2.
 ROCR currently supports only evaluation of binary classification tasks.
 u...@host.com
 


-
Frank Harrell
Department of Biostatistics, Vanderbilt University
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