John Mount takes a deeper look at Area Under the Curve:
I am finishing up a work-note that has some really neat implications as to why working with AUC is more powerful than one might think.
I think I am far enough along to share the consequences here. This started as some, now reappraised, thoughts on the fallacy of thinking knowing the AUC (area under the curve) means you know the shape of the ROC plot (receiver operating characteristic plot]. I now think for many practical applications the AUC number carries a lot more information about the ROC shape than one might expect.
Read on for the explanation.