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Re: [XP] Units of time for estimates

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  • Robert Sartin
    ... Because velocity changes. Having velocity be a map from points to hours makes this easy to understand. Having velocity be a unitless number that maps
    Message 1 of 4 , Jun 29, 2001
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      --- Torben_W´┐Żlm <torben.wolm@...> wrote:
      > I got a hard question from my manager the other day:
      >
      > "Why are 'points' a better measure than 'hours'?"

      Because velocity changes. Having velocity be a map from points to hours
      makes this easy to understand. Having velocity be a unitless number
      that maps "estimated hours" to "actual hours" confuses people. You will
      quote numbers in (estimated) hours and your manager will assume they
      are actual hours.

      Our Master Plan is in points. Every iteration, I update the forecast of
      when I think we will finish by diving remaining points be velocity
      (points per iteration) to get # of iterations to completion. I do much
      less work updating the plan than I used to (pre-XP) when all of the
      estimates were in hours. My updating is more accurate because I use my
      current velocity to forecast everything, and don't try to live in the
      fantasy world of many project plans that assume future estimates to be
      accurate even though all completed tasks have taken longer than
      estimated (or worse yet the ultra-fantasy world where future tasks are
      completed faster than estimated to compensate for completed tasks
      having taken longer than estimated).

      Regards,

      Rob


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    • Ron Jeffries
      ... You guys are starting to convince me ... tell me more, points users! Ronald E Jeffries http://www.XProgramming.com http://www.objectmentor.com
      Message 2 of 4 , Jun 29, 2001
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        Responding to Robert Sartin (08:54 AM 6/29/2001 -0700):
        >Because velocity changes. Having velocity be a map from points to hours
        >makes this easy to understand. Having velocity be a unitless number
        >that maps "estimated hours" to "actual hours" confuses people. You will
        >quote numbers in (estimated) hours and your manager will assume they
        >are actual hours.

        You guys are starting to convince me ... tell me more, points users!

        Ronald E Jeffries
        http://www.XProgramming.com
        http://www.objectmentor.com
      • C. Keith Ray
        ... My team uses a wiki to display to the rest of our company the tasks we are doing this week. Any bug fixes that are demanded but were not originally
        Message 3 of 4 , Jul 2 7:24 AM
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          > Maybe all our trouble started here. She wanted to know exactly why we were
          > not faster. Part of it was significant changes in some of the stories
          > (zeroing out some of the effort spent), but the real time consumers were non
          > project related tasks. Old systems needed attention and servers were
          > breaking down. And probably the hours spent on these tasks were not
          > compatible with the point system. I don't know.

          My team uses a wiki to display to the rest of our company the tasks we are
          doing this week. Any bug fixes that are demanded but were not originally
          scheduled would show up on the this-week's-tasks wiki page. Estimated time
          (in days) and actual time (when a task is done) are listed with each task.

          Since we have about six projects to be done by three people -- most of the
          projects are inactive except for occasional bug fixes, which often have
          'must be done immediately' priority -- it seems to be very important to let
          all the people who demand our time be aware of the other demands on our
          time.

          Sometimes we get them into a meeting or virtual meeting to determine the
          relative priorities of projects, so one or two project can be completely
          ignored in favor or others for a few weeks at a time.

          When you have multiple projects, perhaps estimating stories and tasks in
          [fractions of] days is better than using points. It is also difficult to
          have fixed-length iterations when you have multiple projects -- for some
          purposes, we have one-week iterations, but inactive/bug-fix projects get
          built and deployed whenever a bug is fixed.

          It might even be worth putting meetings (and their actual times) into the
          task list, when the whole team has to attend a meeting of one hour or more.

          ----

          C. Keith Ray
          <http://homepage.mac.com/keithray/resume.html>
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