Rails Test Prescriptions Blog

Keeping Your Application Healthy Since 2008

July 16, 2010: Why Not Four?

Not much time this morning, not many accumulated links. So just a little bit today.

Book Status

Still writing the new parts of the legacy coding chapter, last night a little bit on removing dependencies. I think only one more section to go before that’s a complete draft. Next up, I think, is making the code samples Rails 3 compatible.

One quick thing

Sometimes you don’t realize how weird something is until you try to explain it. I had this conversation last week about Agile planning meetings, with another person who is not familiar with programming details:

Me: And then we estimate the story, and we give it points, we can make it 1, 2, 3, or 5 points.

Other person: Why not 4?

Me: We use Fibonacci numbers, 4 isn’t a Fibonacci number.

Other person: Why do you do that?

Me: [Long pause] Well, um, that’s a good question.

And scene.

I do actually understand in theory why you might want to limit the range of options for story points. You want to make the estimates deliberately coarse so as not to get a false sense that they are more accurate then they are. I also understand why its not worth debating whether a story is a 10 or an 11.

That said, Fibonacci points seems to be something that got popular when I wasn’t paying attention, and it kind of seems to me that, theory aside, 4 is a useful concept in practice for, you know, marking a story that is bigger than 3 points, but not quite 5 points. On our team, we have at least one story in that slot every iteration, and somebody (okay, me) always bemoans that the story should be a 4.

Those of you who want to join this little “Why Not Four?” crusade, should start chanting “More Four! More Four” or “What do we want? Four. When do we want it? Three to five days from now” at your iteration planning game events. Together, we can see a brave new world without an awkward pause between three and five.

(Have I beaten the joke into the ground yet?)

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3 responses to “July 16, 2010: Why Not Four?

  1. Nathan July 16, 2010 at 8:06 am

    We use powers of two, and it surely helped me in understanding the “points” as a representation of the “complexity” of the problem, instead of a mere abstraction of time.

    There was a very good explanation on infoq: http://www.infoq.com/articles/agile-estimation-techniques

  2. mikewoodhouse July 16, 2010 at 10:28 am

    I tend to think it’s really an extension of “one, two, many”: we go to three because we’re super-smart.

    Or maybe we’re Discworld trolls, who count “one, two, many, lots” I’m told.

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