[R] help on ROC analysis

[Wensui Liu]

Hi, ZJ,
In verification package, there is a function that takes observed
response and predicted probability and then calculate the ROC.
I am not sure if it is what you are after.

On Dec 31, 2007 10:27 AM, zhijie zhang <epistat at gmail.com> wrote:
> Dear all,
>   Some functions like 'ROC(Epi)' can be used to perform ROC analyssi, but it
> needs us to specify the fitting model in the argument. Now i have got the
> predicted p-values (0,1) for the 0/1 response variable using some other
> approach, see the following example dataset:
>
> id   mark  predict.pvalue
>
> 1      1       0.927
>
> 2      0       0.928
>
> 3      1       0.928
>
> ..................
>
> *mark* is the true classes, *predict.pvalue* is the predicted p-values,
> which was used to determine the predicted classes. So i need to specify some
> cut points for *predict.pvalue*, and then compare it with *mark*class,
> generate the 2*2 tables, and then calculate some sensitivity,
> specifity....statistcs, and ROC curve.
>  I have searched some functions, such as roc(analogue),'ROC(Epi),etc. They
> may need to specify the fitting model in the codes or group varibles,
> and may be not appropriate for my condition. I think that it should
> have been performed in some package for ROC analysis.
>   Anybody can tell me which function is for this case?
>   Thanks very much.
> --
> With Kind Regards,
>
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> [***********************************************************************]
> Zhi Jie,Zhang ,PHD
> Tel:+86-21-54237149
> Dept. of Epidemiology,School of Public Health,Fudan University
> Address:No. 138 Yi Xue Yuan Road,Shanghai,China
> Postcode:200032
> Email:epistat at gmail.com
> Website: www.statABC.com
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-- 
===============================
WenSui Liu
Statistical Project Manager
ChoicePoint Precision Marketing
(http://spaces.msn.com/statcompute/blog)