# Different shapes of an ROC curve

What are the possible shapes of an ROC curve? Is it necessary for an ROC curve to be shaped like a normal distribution curve?

Can we regard the following two curves as ROC with the area under the curve equal to 0.925 and 0.950, respectively?

• You might state your ultimate goal, and how ROC curves provide insights (if they do) towards meeting that goal. – Frank Harrell Mar 30 '15 at 18:33

Valid ROC curves must be monotonically increasing, start at $(0,0)$ and arrive at $(1,1)$, that's about it. Both shown curves are valid.