Comment by gjm11

I'm not missing the point, I'm disagareeing with it. I am saying that the convention that if you say 20% then you are assumed to have an error margin of 5%, while if you say 19% you are assumed to have an error margin of 1%, is a bad convention. It gives you no way to say that the number is 20% with a margin of 1%. It gives you only a very small set of possible degrees-of-uncertainty. It gives you no way to express that actually your best estimate is somewhat below 20% even though you aren't sure it isn't 5% out.

It's true, of course, that if you are talking to people who are going to interpret "20%" as "anywhere between 17.5% and 22.5%" and "19%" as "anywhere between 18.5% and 19.5%", then you should try to avoid giving not-round numbers when your uncertainty is high. And that many people do interpret things that way, because although I think the convention is a bad one it's certainly a common one.

But: that isn't what happened in the case you're complaining about. It was a discussion on Less Wrong, where all the internet-rationalists hang out, and where there is not a convention that giving a not-round number implies high confidence and high precision. Also, I looked up what Yudkowsky actually wrote, and it makes it perfectly clear (explicitly, rather than via convention) that his level of uncertainty was high:

"Ha! Okay then. My probability is at least 16%, though I'd have to think more and Look into Things, and maybe ask for such sad little metrics as are available before I was confident saying how much more."

(Incidentally, in case anyone's similarly salty about the 8% figure that gives context to this one: it wasn't any individual's estimate, it was a Metaculus prediction, and it seems pretty obvious to me that it is not an improvement to report a Metaculus prediction of 8% as "a little under 10%" or whatever.)