Comment by jcheng
2 hours ago
> Am I missing something?
If you’re sincerely asking…
Mathematically speaking, 18 / 3.6 isn’t “reducing” by 3.6X, it’s “dividing” by 3.6X. Reducing would be 18 - (18 * 3.6), which is obviously wrong. By your formula, “reducing by 50%” would be 18 / 0.5, also obviously wrong.
Yes, people do say things like “reduce by 3.6X” and are understood to mean what you said, but they also say “literally” when they mean “figuratively”. It doesn’t bother me but I can understand why math oriented people would be annoyed, and I personally would never say “reduced by 3.6X”, but instead “reduced by 72.2%”.
I was sincere, because as you point out, the phrasing is not actually ambiguous here. There is only one way to interpret this that is coherent and sensible. The usual % shenanigans weren't even on the table for me. Not that I'd have ever seen "reduced by 0.5x" or any value below 1x, probably for this very reason. What I do see is "reduced to 0.5x", in which case you swap the division for multiplication.
Percentages on the other hand are a whole can of worms, even if these are principally interchangeable, and I find them a lot more confusing a lot more often.
Not that this would explain the mean/geomean thing.