Comment by jrowen

I'll grant that it's complicated, as the comments on this post have demonstrated.

But half the exposure isn't quite equivalent to twice the protection.

All my life I just thought they were somewhat arbitrary numbers, I didn't correlate them to any actual measurable quantity, and I would assume it's the same for most people. So while I would agree that that representation "gets the job done," I don't think it contributes to a deeper understanding.

I do feel like if you saw "90%, 95%, 97%, and 98%" on the shelf it would start to make some kind of sense, and then when people talk about it ("what's the difference between 97 and 98?") the underlying concept would become more apparent. Using a kind of converted magic number scale that doesn't work like other things seems unhelpful, but I'm certainly not an expert nor the intended audience.