[R] How to calculate the AUC in R

[Adaikalavan Ramasamy]

Also see the function AUC in the ROC package.


On Mon, 2005-04-11 at 13:34 -0400, Frank E Harrell Jr wrote:
> Dubas, João Paulo wrote:
> > Hello R-listers,
> > 
> > I'm working in an experiment that try to determine the degree of 
> > infection of different clones of a fungus and, one of the measures we 
> > use to determine these degree is the counting of antibodies in the 
> > plasma at different dilutions, in this experiment the maximum number of 
> > dilutions was eleven. I already checked for differences on the maximum 
> > concentration of the antibodies in function of each clone of the fungus. 
> > However one measure of interest is the area under the curve (AUC) for 
> > the counting of antibodies in function of dilution. Unfortunately I 
> > don't know how to calculate the AUC. Someone can point me an example of 
> > this procedure or a package that implements this calculation?
> > 
> > Thanks for the help,
> > João Paulo Dubas.
> > 
> 
> One of many ways:
> 
> trap.rule <- function(x,y) sum(diff(x)*(y[-1]+y[-length(y)]))/2
> 
>