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Comment by jfoutz | Hacker News Reader

there is an uncharitable response to this thread, which is marked dead. I do think there is a kernel of truth in that response, which is nothing more than mocking.

why fibonacci? I think it's reasonable to say time includes an exponential error. an estimated 1 hour task is very different than an estimated 1 week task. i see that 1 hour, 1 day and 1 week estimates are progressively, and likely exponentially, worse.

Is it just the ease of doing the math? (totally reasonable answer, in my humble opinion). or is there something specific about fibonacci that's actually relevant? I think it's the former not the latter. but if you have any evidence to the contrary, i'd love to hear it.

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The reason my team uses Fibonacci is that it cuts down on the “is this a 3, 4, 5, or 6 point ticket?” discussion. Each larger value should have more uncertainty, so there isn’t any point in getting more precise. Not being able to argue over 1 point differences but having to choose between 5, 8, and 13 has a clarifying effect on the process.

The kernel of truth of that response is that you won't get more certainty about an estimate by adding more uncertainty, no matter in how much pseudo-scientific cargo-culting mumbo-jumbo you cloak it. (Unfortunately, HN readers don't really like sarcastic commentary which requires reader to think it through. Time is precious, and we just want to be coddled, give me your opinion ELI8 straight, because there is no time to think!)

I think you're half right. adding an error band to a far out estimate won't give you a better estimate, but it might help tell you how much you _don't know_ about what you're facing.

Cumulative error is _hard_. see weather prediction.

The reason the Fibonacci sequence is used is because we don't think in an incremental scale but in a logarithm scale. In other words, we think that some simple takes 1 day, a more complex takes 3 and a even more complex takes 5 days. Usually we don't jump from 1 to 2 days when thinking about a task effort.

You could have also used approximately logarithmic scale that everybody is familiar with, namely, cash! You know, 1,2,5,10,20,50,100,200,500..

But no, here we are doing science, that's why we use Fibonacci, hey even plants and rabbits are using it.

I kinda want to grab you by the lapels and re-enact that part from Clear and Present Danger. It doesn't matter what's true, it matters what i can prove!

Unfortunately, the phrasing would be more like, It doesn't matter what's true, it matters what i can sell to management.

In the absence of evidence to the contrary, i think i'm ready to take a side close to yours. It's useful to expand error bars exponentially as you move away from the time of the estimate, but there's nothing special about fibonacci.

> Unfortunately, the phrasing would be more like, It doesn't matter what's true, it matters what i can sell to management.

Yes, that's my main beef with it. SCRUM could be based on science, but sadly, it isn't. Here's an interesting book: https://www.amazon.com/Making-Software-Really-Works-Believe/...

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