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150631Re: [XP] What's a good velocity?

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  • Kim Gräsman
    May 6, 2009
      Hi Dave,

      Catching up on an old message marked for follow-up...

      On Thu, Apr 30, 2009 at 10:59, davenicolette <dnicolet@...> wrote:
      > --- In extremeprogramming@yahoogroups.com, Kim Gräsman <kim.grasman@...> wrote:
      >
      > This comment of yours caught my eye:
      >
      >> Another idea I had was to transpose the scale to, say, (10, 20, 40) --
      >> because the numbers don't matter -- and assume our velocity would be
      >> 70. Then work from that, and try to re-estimate the troublesome fours
      >> into somewhere between 20 and 40, some may be 25, some may be 35. This
      >> would have made the estimation scale more of a continuum.
      >>
      >
      > I think the notion that "the numbers don't matter" means that there's no absolute "good" or "bad" velocity value.

      Yes, that's what I meant.

      > The /scale/ might matter, though, because it can influence the team's behavior in a way that may be detrimental.
      > When teams use scales like these:
      >
      > 10, 20, 40
      >
      > [...]
      >
      > and so forth, there's a risk of falling into a "false precision" trap. I've seen people get tangled up trying to distinguish between story sizes like 18 vs 24, or 197 vs 202, or 1/4 vs 1/5, or 1.5 vs 1.75. IMHO that's a waste of time and doesn't help with problems like having a "cramped" scale.

      Right, I tried to mention this in the paragraph following the one you
      quoted. Thanks for expanding.

      > Instead of adding trailing zeroes, I'd suggest maybe spreading the scale out a bit. If you're finding that realistic
      > story sizes are 1 and 2, why not establish a scale like
      >
      > 1, 2, 4, 8, Too Big
      >
      > or
      >
      > 1, 2, 3, 5, 8, Too Big
      >
      > and then start calling the "old 2" the "new 4" or the "new 5". That gives you some breathing space without inviting
      > debates over falsely-precise sizes.

      "Too Big" is nice, I think working that one harder would yield better
      predictability.

      Thanks,
      - Kim
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