[degamad]

> The only thing that matters in this kind of application is false negative rate at some acceptable false positive rate.

It sounds like they are inverting the scenario here. The question is not "do you have skin cancer?", it's "can you safely go home without seeing a doctor?".

For this new question, we set the acceptable false positive rate to zero (we never want to send a real cancer case home), and determine the false negative rate (we accept that some benign cases will be seen by a doctor).

The reason for the interest in identifying benign cases, rather than trying to identify the positive cases, is that it improves the situation for everybody: benign cases identified by AI are sent home almost immediately, everyone else has a shorter waiting time, so benign false negatives can be assessed more quickly by the doctor and given the all clear, and more time is now available for spending with the real cancer cases.

The numbers they're citing are 7000 cases with 5% real, so 350 real cancer, 6650 benign. If we can accurately say that 6500 of those benign cases are benign without wasting the doctors' time, then we're down to only 500 people needing to see a doctor, which is a huge improvement for everyone.