[vostok]

I really like the table of confusion as a way to look at this stuff. I find the terminology somewhat confusing and it's much easier for me to just look up the formulas.

That means 90% accuracy should mean (true_positive + true_negative)/(whole_population) == 90%.

https://en.wikipedia.org/wiki/Confusion_matrix

[diffeomorphism]

So a trivial test that always says "No" will have better accuracy?

https://www.cancer.org/cancer/types/prostate-cancer/about/ke...

> About 1 in 8 men will get diagnosed with that cancer, through their whole lifetime.

So true_negative/whole_population>=87.5% at least (life time vs currently has cancer).

Or am I misunderstanding the meaning?

[greenavocado]

This is why accuracy is useless for reasoning about detection of rare things.