Re: st: diagt and accuracy

[Ron�n Conroy <rconroy@rcsi.ie>]

heg2001@med.cornell.edu wrote:

> Originally I wanted to have ROC area (as calculated in -diagt-), but I 
> was
> told that with a dichotomous test ROC area wasn't relevant, ie, I didn't
> have different cutpoints at which to operate the test. That's when she
> mentioned accuracy defined with prevalence.
>
> In fact, ROC area doesn't account for prevalence either...
The ROC area is still useful, because it is the Mann Whitney statistic - 
the probability that if a person with and a person without the condition 
are taken at random, the person with the condition will have the higher 
score. In clinical trials, it becomes the probability that a person on 
the superior treatment will have a superior response. Both are very 
useful clinical information.

r
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