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?
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.