[humanrebar]

> It's not a bad thing to do a lot of estimating up front so the business can make an informed decision about whether it really wants to commit to the effort...

You're assuming the estimate is worth much. Which is what much of the industry is doubtful about. To underscore the point, most estimates are single values (eight months), not confidence intervals.

A better answer would be, "There is a 50% chance that we get it done between six and seven months from now, assuming requirements don't change."

...but even that assumes that all along the way, the project stakeholders are keeping in mind how many (how do you quantify?) requirements were added and discovered.

[a3n]

How it's said: "There is a 50% chance that we get it done between six and seven months from now."

How it's heard: "Wa wa wah, wa wa, we get it done between six and seven months from now."

[DougWebb]

You forgot the "assuming requirements don't change" part.

What's actually heard would be "Wa wa wah (up to) six months from now (guaranteed) wa wa."

[cableshaft]

Yeah, and they'll push for four months total at a meeting a month into the project, while simultaneously changing their mind on a half dozen requirements.

[phyllostachys]

Ugh. I was on a project like this. I figured that it was mostly just that specific customer...

[cableshaft]

...Unfortunately, there's a lot of "specific customers" like this.