Hacker News Reader

Comment by AnimalMuppet | Hacker News Reader

One place I worked said that you weren't allowed to make an estimate that was longer than three weeks. There are apparently studies showing that estimates longer than that tend to have much larger errors. So if it was going to be longer, we had to break it up into pieces until each piece was smaller than three weeks.

That could get tedious. On the other hand, we did do a lot better than normal at hitting our dates.

(I believe this shorter-than-three-weeks idea came from Extreme Programming, but I'm not quite certain of that.)

View on HN

This is also why I like estimating tasks using the Fibonacci scale without a direct correlation to time.

In my teams, we generally set 8 points as something that would take an entire day. Every number after that jumps up in relatively large increments as they are more difficult to accurately determine

Interesting take, mind sharing how do you use fibonacci ? Thanks

https://www.youtube.com/watch?v=iZYSapFCg4A

Not the OP, but one of the teams I'm on uses fib somewhat differently.

Any point with 1-2 is estimated at < 1 day. Some are literally 20 minute fixes, but ... you don't always know that up front, you just generally know it may be pretty small. 2 might sometimes go up to a day.

A 3 is assumed to be a day or two.

A 5 is assumed to be 3-4 days.

An 8 would be 1-2 weeks.

Anything higher is backlogged until it's broken down into smaller segments.

Not sure how well that compares to usages by other teams, but that's one data point for your question.

But then, you still have to connect all these 3-weeks-pieces together. And how long does that take?

No we are back to the original, overall question...

The idea was that the three week pieces add up to the whole of the larger task. (Yeah, I know - only if you didn't miss anything. Take the time to think it through well enough that you don't do that. And what if you have things you don't know? Then you have to do a research project to find them out before you can give valid estimates.)

"And what if you have things you don't know?" I usually find stuff out in the middle of work - a question comes up I don't have an answer for, and many times, no one else does either. In effect, no one can estimate it, but we didn't even know that up front. And... I've often hit things where the time to give an 'accurate' estimate takes more time than the actual work effort. Is that common in your "limit everything to 3 weeks" world?

If the time to give a more accurate estimate takes more time than the actual work, you aren't dealing with an estimate longer than three weeks. If the estimate is less than a day, it's not worth getting more precise.

To your first point: Yes, that happens sometimes. When it does, your estimates can be wrong. (Hey, they're estimates - they're not prophecies.) If that happens very often, though, you might add a fudge factor for "that kind of thing". Maybe something like "unknown surprises crop up most of the time, and when they do, they take about 20% of the effort, so we'll make our best estimate, then add 20%". That won't be perfect either - sometimes it will be 40%, and sometimes 0. But, you know, estimates...

Reply on news.ycombinator.com