[jph00]

> I don’t know how to trust the author if stuff like this is wrong.

She's not wrong.

A good way to do this calculation is with the log-ratio, a centered measure of proportional difference. It's symmetric, and widely used in economics and statistics for exactly this reason. I.e:

ln⁡(1.2/0.81) = ln⁡(1.2)-ln⁡(0.81) ≈ 0.393

That's nearly 40%, as the post says.

[nkmnz]

so if the numbers were “99% slower than without AI but they thought they would be 99% fast”, you’d call that “they were 529% slower”, even though it doesn’t make sense to be more than 100% slower? And you’d not only expect everyone to understand that, but you really think it’s more likely a random person on the internet used a logarithmic scale than they just did bad math?

[ozozozd]

Well, this random person we are referring to happens to have a PhD in math from Duke.

I find that satisfying.