Comment by peeters
4 days ago
So the context of the quiz is software estimation, where I assume it's an intentional parable of estimating something you haven't seen before. It's trying to demonstrate that your "5-7 days" estimate probably represents far more certainty than you intended.
For some of these, your answer could span orders of magnitude. E.g. my answer for the heaviest blue whale would probably be 5-500 tons because I don't have a good concept of things that weigh 500 tons. The important point is that I'm right around 9 times in 10, not that I had a precise estimate.
I don't know, an estimate spanning three orders of magnitude doesn't seem useful.
To continue your example of 5-7 days, it would turn into an estimate of 5-700 days. So somewhere between a week or two years. And fair enough, whatever you're estimating will land somewhere in between. But how do I proceed from there with actual planning or budget?
> But how do I proceed from there with actual planning or budget?
You make up the number you wanted to hear in the first place that ostensibly works with the rest of the schedule. That’s why engineering estimates are so useless - it’s not that they’re inaccurate or unrealistic - it’s that if we insisted on giving them realistic estimates we’d get fired and replaced by someone else who is willing to appease management and just kick the can down the road a few more weeks.
Your question is akin to asking ‘how do I make the tail to wag the dog?’
Your budget should be allocated for say 80% confidence (which the tool helpfully provides behind a switch) and your stakeholders must be on board with this. It shouldn’t be too hard to do since everyone has some experience with missed engineering deadlines. (Bezos would probably say 70% or even less.)
I mean it's no less useful than a more precise, but less certain estimate. It means you either need to do some work to improve your certainty (e.g. in the case of this quiz, allow spending more than 10 minutes or allow research) or prepare for the possibility that it's 700 days.
Edit: And by the way given a large enough view, estimates like this can still be valuable, because when you add these estimates together the resulting probability distribution narrows considerably. e.g. at just 10 tasks of this size, you get a 95% CI of 245~460 per task. At 20, 225~430 per task.
Note that this is obviously reductive as there's no way an estimate of 5-700 would imply a normal distribution centred at 352.5, it would be more like a logarithmic distribution where the mean is around 10 days. And additionally, this treats each task as independent...i.e. one estimate being at the high end wouldn't mean another one would be as well.