Doesn't work. For instance in a business setting, if I say "it'll be done in 10 days +/- 4 days", they'll immediately say "ok so you're saying it'll be done in

Doesn't work. For instance in a business setting, if I say "it'll be done in 10 days +/- 4 days", they'll immediately say "ok so you're saying it'll be done in 14 days tops then". More effective to sound as unsure as possible, disclaim everything in slippery language, and promise to give updates to your predictions as soon as you realise they've changed (granted this wouldn't work as well for an anonymous reader situation like in this article).